I have had to have many Serious Talks with my best friend on why she is not to mack on my brother. Mainly, because he's a colossal shithead and she dates lots of shitheads, and I'm tyring to break her of the habit. Otherwise, I wouldn't mind.

This troper knows someone who has third degree UST with his friend's sister. They're pretty much in a relationship by default. Partially subverted, because the brother doesn't care, but the guy insists on enforcing the trope anyways and not actually going out with her. Except that they're sex friends, for some reason.

This troper's father fell in love with his good friend's sister-''in-law''. Didn't stop the friend from being extremely pissed when said sister-in-law turned out to return the feelings. The friend got over it, and this tropers parents have had a reasonably happy marriage currently over 25 years strong.

This troper's older brother once did this in front of his entire baseball team. His exact words? "That's my sister. Don't touch her in any way other than a 2 second hug. I will beat you senseless, even if she makes the first move. Now, who wants hotdogs?"

This troper went to an all boys school where talking about girls can be... colorful to say the least. The one house rule: Talking about sisters were off limits.

This Troper also goes to an all boys school with just as colorful conversations regarding girls. This is an aversion as talking about sisters may as well be the school's sport.

This troper talks to someone on another message board, who likes to joke that this troper isn't allowed to date his sister. But this troper hasn't met or even seen a picture of the lady in question to decide if he's interested. And he's so insistently brought her up for no reason at all that this troper is starting to suspect things...

In this troper's most recent yearbook, there is a "Siblings Page", on which there is (among other things) a picture of a senior guy and his sophomore sister. He is holding a sign which reads "She Is Not Allowed To Date". [Update: Didn't work.]

This troper won't let you have his sister. You don't want her anyways.

Are you sure we wouldn't?

Exception: This troper once had a friend who, while never expressing it out loud, seemed to hint more than once that it would be okay for me to date his sister. Nothing ever happened though, since said friend and sister looked fairly...similar...

Seth? Is that you? (This troper and his sister did have very similar looks back in grade school, though she was always cuter. There isn't nearly so much similarity anymore, especially since he started wearing a beard.)

Inversion: One friend of this troper's friends once joked that it would be funny if she (friend) was going out with her (troper's) brother. The immediate answer was "'''NO'''". Mind you, this troper and said friend have a relationship like Spongebob and Squidward, with friend being Spongebob and troper being Squidward, and this troper would shoot her friend for being annoying, her brother for being stupid enough to date her, and then herself for the torture that could have happened.

This troper knows a very obnoxious {{Jerkass}} with a very hot older sister. He is extremely protective of her, to the point that troper suspected BrotherSisterIncest until the subject came up through other means and she flatly denied it with a very, very, very {{Squick}}ed look on her face. The fact that {{Jerkass}} looks to be roughly eight and the older sister is, er, to put it simply a gigantic walking piece of pedo-bait (she's 18, but looks a little over half that) may not have helped.

This troper had this speech off a friend - and promptly ignored him and attempted to get his sister into bed. As we were both consenting adults I saw no reason why he had any justification for trying to control who I (or her) slept with.

This troper once got a strong talking to from a friend for not noticing his sister who, obviously to everyone but me, was clearly very much attracted to me...

Inverted by This Troper's best friend, who said he'd be stoked if he (troper) married his (friend) twin sister. Alas, it is not to be.

This troper's brother just got married. To a woman who nearly got him arrested and seems to be out for his money. This troper got overprotective. Her brother is ten years older than her and they haven't seen one another in a little over 8 years.

I reverse this. I have told my friend's sister many times that ''I'' am off-limits. She doesn't seem to be deterred by this, unfortunately.

I've had inversions of this. In high school, I was the guy who was too nice for his own good. People regularly tried to match me up with their sisters.

This troper will claw out the eyes of any girl who hurts her baby brother.

This troper is the sister of this trope. Both her brother and her father has smilingly said that they'll kill anyone who tries to lay his hands on her before she's thirty. Bummer.

Interestingly, this troper gives the smiley "Boy, I'd sure hate it if something had to happen to you..." version to her sister's boyfriends, and said sister gives the straightforward "I will KILL YOU if you do something stupid" to my potential interests.

Some sort of crazy inversion happened when this lesbian troper came out to her best friend's little sister. The response was, "You'd better not start dating (best friend's name)".

This troper has had a crush on his friend's sister that meshes with this trope and the fact that he has grown up alongside the two. This troper has never acted on it, seeing as she's slightly underage, but the brother doesn't openly invoke this trope. Hilarity ensues at times when this troper creates squicky hypothetical remarks in front of him, though.

Subverted, in my case because one of my friends asked me who I liked then I responded with "your sister". From that day he kept on pushing me and made me ask his sister out and when I was rejected he now tries to "improve" me and make me practice to ask her out again. I was only joking around though

In high school this troper inverted this trope. A friend came up nervously and asked if he could date my sister. I said I didn't care as she can make up her own mind. I was secretly smiling to myself because I knew he wasn't going to get laid. Later, same friend came up to me nervously about 3 months later and said he wanted to break up with her. I laughed and said "Didn't get laid, hunh?" which is reluctantly admitted.

This troper's younger sister has recently started recieving friend requests from guys she doesn't know. I have recently started sending messages to them.

This Troper's little brother found a condom in my cousin's room which was for our older step-brother. I couldn't believe what it led to

This Troper's sister is currently married to a guy that he was friends with in high school. Aside from one joke wherein This Troper played the stereotypical "mean older brother" for a laugh, the day before their wedding and several years after the two started dating, never once did he question or discourage this relationship. Take that, tired cliche!

Averted oh-so-hard by one of this troper's friends and another friends' little sister. They have been dating for well over two years and are currently living together.

Both explicitly and implicitly stated to be the case with two of this troper's good friends. In the former case, it's not such a problem because I have known the sister since she was eleven and there's less temptation there. In the latter...not so much.

Update: Ahahaha I can't believe I ever thought that. It's increased from two to three, the trope has been made explicit in two cases and in the third, another friend has already been there, done that and is hiding the fact at all costs.

This troper's best guy friend feels this way about me. Sometimes it's endearing, but most of the time it's damn annoying. XD

This troper's brother told his best friend to stop making puppy dog eyes at me during his Bar Mitzvah. It didn't work, it's been three years and it's starting to creep me out a little.

This Troper... oh dear.... #QUOTE# ThisTroper: "Damn that ho's fine." #QUOTE# Friend (Not for much longer): "That's my sister." #QUOTE# ThisTroper: "Damn your sister's fine."

Well.... if you are going to stick your foot in your mouth, you may as well stick it in all the way.

what she said!

The above troper has been shot. ''That'' is what she said.

This troper has a friend who was a complete aversion of this trope. He couldn't have cared less who dated his sister. He was a bit apathetic that way.

This troper experienced a highly weird version of this trope: she's a bisexual woman, who met a guy and his younger sister and happened to get along quite well with both of them. The brother seemed to find himself stuck somewhere between "if you touch her I will hurt you" and "would you like to go out with me sometime". (Nothing ever came of it since the troper moved to a new city before it reached any kind of crisis point, but for what it's worth she preferred the brother as she felt the sister would have been too young for her.)

This troper is often asked by her classmates if she has any older siblings (which I indeed have; one brother and one sister). Her response? "I do, and he/she is way too old for you."

Both straight and averted by my brothers. They have made it quite clear that the average human male is nowhere near good enough for me, but helpfully provided a list of people I am allowed to date. While the majority of the list were things like "Jesus" and "Atticus Finch," the last name on the list was the sibling of my brother's best friend, and it was circled and underlined several times. Subtlety is not a word that can be used to describe my family.

This troper's younger brother has recently shown that he will harm anyone she ties and bring home when she goes to college next year. It's gotten to the point that this fact ranks highest on the list of reasons not to tell her family about her boyfriend- above "I live in Texas, he lives in New Zealand."

This troper younger sister had told her friend who had a crush on me that I'm in college, I won't date a tween and she shouldn't keep hope so apparently I'm out off limits. She also is for my friends. I'm six years her senior and no one can mention she being beautiful even that gay friend I know since we're five.

I have never understood this. If I had a sister (it could maybe happen with one of my female friends, but they can take care of themselves) I wouldn't mind if she dated my friends for two reasons. One: I know them; they wouldn't hurt her. Two: It's not my decision; it's hers.

Slight subversion: this troper's best friend recently informed her that this troper is exactly her brother's type.

Inverted by this troper's friend - after learning that I'd had a crush on her older brother for the past year, she immediately commented that I was really similar in personality to both him and his ex-girlfriend. She's now in the process of trying to convince me that I should try to get closer to him, as she thinks we would go together well.

This Troper didn't even know that he was guilty of this until he and his brother were hanging out with a mutual friend at our place, and the friend found some photos of our sister, commenting on her hotness. He later revealed that he almost shat himself when we turned, in unconscious unison, and did our best to glare a hole through his skull. Now, this guy is a nice guy and all, but not the kind of guy anyone would want dating his sister. Ever...

This troper is especially guilty of this, seeing it fit to chase the throngs of horny teenaged boys and delinquent friends away from her dearest sister (who is five years her junior) by embarrassing them away. One day my sister brings this troper some of her school. "Who are you?" I say to one of them. "And why are you wearing your school socks like that? Are you some kind of gang member? Are you flashing your gang colours at me? I don't let my sister talk to gangsters and you'd better fix your bloody socks before I fix 'em for you."

One day this troper sees my sister talking to a strange boy. I see her point at me and motion me over so I come and she introduces me. I greet him. "Hello there. You're a handsome young man." I say. "Quite young too. I know how you young men can be, all eager to play the field and have a bit of fun. It's all well and good until someone's got a bun in the oven. So let me tell you something, if I have a niece before my sister is thirty I'm coming for you and it's such a shame for nice, handsome young men to end up in the river. OK ta-ta. I'm watching you two," I look at my sister. "And I better not see any making out over here."

This troper's drama class has been doing improv together for a year and a half now, and they have developed a ridiculous litany of recurring jokes, including that the nicest guy in class will punch you out for even looking at his hot sister. (He's an only child in real life.)

Complete aversion: When This Troper started crushing on his friend's sister, the friend in question said, and I quote, "I don't care". This Troper and the friend's sister dated for a good eight months and broke up on happy terms, even. But, played straight in that This Troper hasn't been as close with the friend since.

This troper has been confronted with this and just wants to know why it's okay for the sister to date random guys that the other sibling doesn't know, but people said sibling does know, and would be easier to control through the friendship with them, are not allowed to date them. A case of "I'll be good to your sister, even if only because she's ''your'' sister."

This Troper's sister starts high school next year... I think that explains it...

This Troper's older sister is an aversion. Nearly every conversation we have ends with her asking if this Troper has a boyfriend, and if not, she apparently has many friends she can set me up with. Joking or not, it's pretty creepy considering she's 7 years older and graduated college already, and this Troper is still in highschool.

I was at a party in a friend's basement when his sister came downstairs with some of her friends and started talking with the friend. I was standing nearby and asked who he had been talking to. He mentioned that she was his sister and was about 15 (We were 17-18.) He then said not to get any ideas about her. I was drunk and jokingly said "I can't promise anything." He gave me the evil eye and I backpedalled really quickly.

This troper has a funny situation. See, she would love for one of her friends to date her little sister, and the guys has shown interest... but the little sister is a lesbian. She really is off limits.

"My name is Joe, and I'd like to take your sister Flo to a show. Can she go?"

"My name is Eddie, and I'd like to take your sister Betty for spaghetti. Is she ready?"

"My name is Chuck and-*BLAM BLAM BLAM*