When I played High School sports our basketball team would sometimes go on the road with the girls team for budgetary reasons and we would instigate the hell out of the away parents/fans. It was funny at the time but I grew up and wouldn't do it now.
My proudest moment in teenage assholery relating to sports came at a hockey game. My school was playing our rival school and we found out that their best player who was 16 had been fooling around with a 13 year old girl. We taunted him until he became so infuriated that the coach had to pull him from the game and we wound up winning.
On the flipside I was at a university hockey game when I was in college and this one guy there was just going crazy and making everybody uncomfortable. The rink seats were like these long bench seats and no one was sitting within arms length of him so I went over and sat very close to him, like leg to leg. So he starts saying shit like "What the fuck are you doing, go sit somewhere else" I just ignored him looked straight ahead. He gets up and starts yelling at the ref/players and I stood up and kind of stuck my body half in front of him without acknowledging him at all. He changed seats and I followed him and kept doing it until he finally just left the rink. My friends still get a chuckle out of it till this day.
