If not for gossip, there's this:
In my high school, the popular kids were all very involved in the school spirit aspect and were all in ASB. If you're unfamiliar, ASB is like the student body government. Whenever the school asks something of its students, the ASB are the first to oblige. Starting in my Sophomore year, a teacher had been pushing for something called "Breaking Down the Walls." These walls were metaphorical barriers created between students whether they be by race, gender, interests, class, etc. So occasionally these people would just walk right into my group of friends and try to join the conversation.
They failed to realize how awkward that kind of action is. Not only that, but these kids were all generally dumb as bricks once you pulled them out of their AP classes (which I took as well, but never fit in because of how... synthesized everyone's personality was). So they'd join a conversation in the open with people they only knew through classes without having any prior knowledge of the individual mannerisms or colloquialisms or in-jokes or anything, then on top of it all they most likely didn't have the intelligence to keep up with a conversation that wasn't about partying, top 40 bands, popular culture, surfing, etc.
Before someone guesses, I wasn't even GAWF or antisocial in school. We would have welcomed anyone into our little circle, but arbitrary intrusions just don't socially work.