Regular Show S06 E24 Brilliant Century Duck Crisis Special

"It's anything but."

In an homage to all things mecha anime, Mordecai and Rigby have to get rid of a cassowary in the park, which turns into an epic battle over merchandising rights when the baby ducks and full-grown geese return to enlist the help of the park workers to defeat a pair of lawyers and their iron-clad contracts.