Not by a Cal player, but Andre Iguodala threw one down against us on a crowded fast break that just took my breath away.
Years ago, in Harmon, Marques Johnson threw down a tomahawk in the half court set that briefly left everybody wondering if they really had just seen what they saw. I wanna say it was his senior year. North basket. He drives, everybody expects to see him try and lay it in, then suddenly realizes he's going to dunk it, then he pulls it back right before he slams it for added emphasis. Crowd went silent, except for gasps.
Among Cal players, as someone mentioned, Roy Fisher was the first Cal player I remember with a number of impressive dunks. What was the name of that white guy, 6-4 PG, who slammed one down left-handed his freshman or sophomore year, then slowly faded into oblivion. He was supposedly one of the guys that Campanelli "ruined". Dude's name is on the tip of my tongue...