Vallejo's CMOA: Personally threatening the son of a Canadian ambassador who abuses his diplomatic immunity, knowing full well it lies outside his jurisdiction and that his title of junior-commissioner could be suspended. Note this also happens after his two best officers quit the safety patrol to take care of the perp and his gang on their own, after he nagged them about leaving said kid alone. Vallejo would have been obligated to take Fillmore and Ingrid's badges, and he cares about the two enough to not want to be the one to do it. You know he knows what's at stake, and he goes through with it anyway. Also counts as a Big Damn Heroes moment.
Vallejo: We may not be able to officially bust you, but if you cause any more trouble in this school, the entire Safety Patrol is going to turn your life into a nightmare from which you will never wake. Am I making myself clear?
And how about every Chase Scene in the entire run of the series?
The end of "A Forgotten Yesterday", in which the culprit is Out-Gambitted by Fillmore.
Fillmore managing to beat the school mini-golf club so hard that he won every trophy they'd ever won in a row, solely because they wouldn't let him join. Yes, it was a horrible thing to do, but he managed to beat all of them in what was implied to be one day. That takes serious talent.
And then he tops it by being man enough to admit it was terrible and make amends.