"A Bunch of Baby Ducks,"

The main Regular Show episode featuring ducks is titled "A Bunch of Baby Ducks," where Mordecai and Rigby find adorable baby ducks that turn out to be dangerous martial artists, leading to chaos and a giant duck fight. They also appear in the multi-part "Exit 9B" and the epic "Brilliant Century Duck Crisis Special," which features giant ducks and geese battling it out.