For the parent, it had to be one of the moms from back when I coached JV. She did the PA system for stadium games (which were only ~3 games per season). Her son--a 9th grader--scored a goal and tore off his shirt in the goal celebration. All of the sudden the PA system clicks on and the announcer--again, this 14 year old's mother--shouts out "take it all off, baby!" You have never heard a stadium go from loud to awkward silence so quickly.
For on the field, it's one of two--both involving SUPER nerdy kids. When I played in HS, we had a kid on the team who was really quiet and passive. Had decent skill, but he was a perpetual bench warmer because he had no aggression whatsoever. One game, against the worst team in the county, the starters were all out (blowout before halftime) and the whole bench was in. Nobody is paying much attention, and then suddenly all hell breaks loose. The passive kid was apparently sick of getting fouled by a kid on the other team, so he literally picked him up, complete with mid-air WWE style hesitation, and body slammed him to the field. It was the most ridiculous thing we'd ever seen the kid do.
The other one involves one of the nerdy kids from the team that I coached. We were getting set to play the best team in the county. They had an amazing striker--literally, they just had to give this kid the ball at midfield and odds were good he could turn it into a goal. Our team had a very good defense, but that striker tore up other teams that had good D as well. We talked strategy all week--I wanted to go with a 2-sweeper 5-man backline, leaving a man free to double team the star striker. Some of the kids wanted to wreck him early and deal with the carding/consequences (we literally had to have a meeting to inform them that anything like that would result in expulsion from the team). Our regular starting sweeper, the team captain at that point, said he had a game plan figured out, and to leave it to him. This was a super nerdy kid that knew from middle school that he wanted to grow up to be a dentist of all things (and yes, he's a dentist now). The game starts, the striker from the other team gets the ball, and just dominates his way down the field. He gets past out defensive mid. Past a couple of our defenders. Our sweeper steps up to him, and the striker gets this weird look on his face, trips up a bit, and our kid stops him and sends the ball back out. Over and over again, it played out. We won the game 2-1 (the kid got a goal when our sweeper was off the field getting treatment for a strained hamstring). Our sweeper's strategy? Every time he got within earshot of the other team's striker, he started going over his chemistry notes, like the two of them were part of a study group. Every single time. Equations, expected lab scenarios, hypothetical test questions, etc etc. He just nerded at him all game long, and it freaked the kid right the eff out.
Was. Not. Expecting. The. End. To. That. Story.