The A's have a scoreboard promotion that they like to do on Two Dolla Wednesday. Because BART sponsors the evening of discount baseball (it's officially known as "Double Play Wednesday"), there's one inning break where the announcer implores the crowd to stand up and wave their BART tickets, in hopes of winning an unspecified prize. It never fails to get the crowd on their feet, shaking their flimsy paper tickets like Polaroid pictures.
(What's cooler than being cool? Not waving your BART ticket in the air like a jackass. Alright alright alright alright alright alright alright alright alright alright alright alright alright alright.)
The Giants have a very similar promotion, but with one subtle deviation. I feel this difference illustrates the fundamental distinction between a crowd at AT&T née Pac Bell Park and a crowd at the McAfee née Oakland Coliseum. In San Francisco, fans don't wave BART tickets; they wave VISA cards.