{{This troper}} and her boyfriend, despite only doing oral. {{This troper}} was going down on her boyfriend while he was playing COD live with some friends. He started making mistakes, and got "Are you getting it on?" Awkward silence...

...Anthony? Is that you?

A friend of mine who tends to take his gaming rather seriously shrugged off a couple of stupid mistakes from team members one afternoon, leading to the obvious question. Thing was, his friends thought they were being funny (he was significantly less experienced than they were), until the several minute silence. Yeah...

Happened to {{this troper}}. I came into work with a big grin on my face, and it was the first question asked.

This high school troper once saw a maths teacher with a big grin making his way down the corridor. He was intercepted by another maths teacher (female) who started giving him little friendly punches in the shoulder and yelling "YOU GOT LAID."

My girlfirend and I visited a castle, there were very few visitors that day, so we went to the Countess' chamber and ... ensued. Later, we met Father John, a priest I know. He calculated the whole situation from the fact that I was wearing my Sunday clothes on a Monday. Therefore, Sunday night, I had not slept at home.

.......Is Father John Batman?

{{This troper}} has on two separate occasions known when people had sex completely from intuition. The first time was sophomore year of high school. I saw a friend sitting at the cafeteria and knew immediately even though she acted no different from usual. The other time was junior year of college when again, I saw a friend across the dining hall and called him out immediately. Once again, he wasn't acting any different from usual. This doesn't work on people who have sex all the time. It's a strange power; fear people like me making your life just a little more awkward thank it was before.

This troper's brother was a virgin when he ran away to New York with his boyfriend. When he came home for Christmas, he was way, ''way'' more upbeat than usual. We were all quite proud of him.

{{This troper}} once got to one of his classes... 25 minutes late because he didn't feel like going to class. Cue different variations of this question being asked when he sits down.

This troper's best friend tends to be in a good mood after having virtual sex in chatrooms.

This is a {{running gag}} for characters in my FanFiction; a 13 year old girl figured it out just by looking at her older brother's smile one morning.

{{This troper}} came home from staying at a female friend's house after playing D&D that night with a group of friends. His mother watched him for a few seconds, and said "You're not a Virgin anymore, are you?" I was happy to finally get that monkey off my back at 19.

Yes... Dungeons & Dragons lead to my lost virginity.

That...is AWESOME!

Hax

{{This troper}} once had this facetiously asked of her after coming out of a practice room with a male friend she had a duet with and (allegedly) had messed up hair. The twist being that she and her friend were twelve and eleven at the time.

ThisTroper has a friend who can tell if people had sex recently. When asked, he explained that he could "smell it". Sounds sarcastic but he does have an incredibly sharp sense of smell.

I had this happen to me after the first time I had sex with my ex girlfriend. I went out with friends the next day and the first thing one of them said was "you totally got laid, didn't you?" I never know how people can tell just by looking at you.

It's more about smell than sight, due to the fact that humans have a kind of pheromone receptor in their noses (they also have a deposit of iron beneath the ethmoid bone that points them toward magnetic North, but that's another trope).