I've been in two minor ones. As a freshman in college I instigated one in an intramural BBall game, where I shoulder brushed a guy and he shoved me. He got a tech, but I instigated it. Don't even remember why.

About 5 years ago in a corporate Ultimate Frisbee game this jerk was jawing at people all game long. I was guarding him and he kept smacking me with the frisbee until I had enough and told him to back off. He started jawing even more but it didn't escalate further. Those are my two closest calls.

I did see once where someone had to be escorted out of an EQ game because both he and the other guy probably would have gone at it in the parking lot.