Me and a few friends were flying to London (we live in Sweden) about a year ago. On the plane, there was a whole group of teenagers who seemed to know each other (after a while we figured out that they were probably going there with their school or something), and one of them thought it very funny to excitedly shout "London, baby!" at the top of his lungs every five minutes. At the beginning, it was sort of funny (or, at least not unfunny) but after a while it started to get very annyoing and his mates started to tell him to shut up every time he did it. Then he stopped doing it for about an hour, but by then it had turned into an
overly long gag, so when he did it again the very second we landed at Heathrow Airport, the whole plane exploded in laughter. Me and my friends still say it to each other from time to time.