Instantly Destroy Buildings
Pick up a gasoline truck and throw it at a building to instantly destroy it.
Control Loading Screen
While the game is loading, press any button and the monster you selected will make funny noises.
If a policeman is after you, lure him away from his vehicle and kill him (kick, eat, grab and jump, ground smash, etc.). If you do not destroy his car, no more police officers will arrive (excluding S.W.A.T. or army tanks).
Go to a billboard on a roof and kick it to change it to a funnier version. For example, in Las Vegas by the large slot machine there is a "Beauty's Only Skin Deep" billboard. Kick the woman in the face to see the girl from The Exorcist.