In MLB 09 The Show gamers can record cheers and cat-calls that will be played during the game. You have to love technology. My suggestions....
For Phil Coke's starts : We got Coke, you don't even have Pepsi
When we get a hit against Papelbon: Who's dancing now?
For Blue Jay games, pending the rest of the NHL season: We're better than you at Baseball AND Hockey.
If they have the pre-season exhibition games against the Cubs: One Hundred Years, One Hundred Failures.
Against the Mariners and Rangers: A-ROD, A-ROD, A-ROD
Whenever playing against Carl Pavano: No Return, No Return, No Return
Against the White Sox when Wilson Betemit is at the plate: Record an Alarm sound for the steal where we got Swisher.
Ok, so my suggestions aren't great. I'm sure you can do better. Let's here ideas in the comments, but use comic book language for profanities (eg. $#!%).