After a home run is hit (while the batter runs towards home) press "L3" or "R3" and the batter will taunt the crowd.

If you want to unlock the Austin Dingers in batting practice then press L2+R2+L1+R1 simultaneously. It wont make any sound and will be right next to the Cooperstown Legends.

Enter exhibition mode, then repeatedly press L2 + R2 until the sound of a dong is heard. The Dingers and Islanders will now be selectable under the 90's teams.