I'm going way back but two stand out to me, both from the 80s. One was the out of bounds play that Moe Iba ran for Greg Downing to get the alley oop. Seemed like it was good for one good dunk game.
The other was Dave Hoppen's freshman year. His first few dunks were less than impressive. I think he was getting some grief from the guys on the team, especially Terry Johnson.
Then one game, I don't remember which, he is coming down the court on a fast break and gets feed for the dunk and he throws it down hard and the bench went wild. Nothing fancy, but memorable.