A couple from my college years:
We always played a really rural school in Mississippi as kind of a goodwill game, and my freshmen year, we had to clear car parts and broken glass off of their infield prior to the game. Apparently they partied hard the night before.
During an extensive rain delay, we built a 9 hole mini-golf course in the clubhouse and had a tournament using fungos and baseballs. During that same rain delay my catcher put his pants on his torso and his jersey on his legs and went sprinting into the drenched infield - looking like some who could run extremely fast while doing a handstand.
Two of my friends "pre-game warmup" was playing a make believe ping pong game using gatorade cups. If you position your hand right, you can flick the side of the cup and it sounds JUST like a ping pong ball being hit. They would play all of these dramatic points hitting fantastic slams and diving saves. Really entertaining actually haha.
The opposing student section was getting particularly nasty with some comments, and our bus driver went over and threatened that he had a handgun in the bus. That didn't sit well with a lot of people. Great story though.
I'm leaving a few others out to keep things G rated.