A truly spectacular example (and equally marvelous send-up) is the kung fu dinner theatre sequence from Meet the Robinsons.
In The Parent Trap rip-off It Takes Two (starring Mary-Kate and Ashley Olsen) there's a food fight that was started when one of the twins tripped a boy carrying a bowl of macaroni to cover her escape. The bowl flies through the air (in Slow Motion) and lands on Steve Guttenberg's head. Kirsty Alley can't cover her laughing, and he flicks a tab of butter at her. She stands up, and declares "FOOD FIGHT!"
In the first episode of Ultimate Spider-Man, some villains break into the school and demand that Spider-Man give himself up. Pete promptly calls a food fight and sneaks away while it's taking place.
in wander over yonder wander starts one with the wtatchdogs in the prisioner hurting peppers in his eye face with ht sauce, lemon and pepper