Regular Show 3x35 "Prankless"

Muscle Man was pranking Mordecai by duct taping his mattress onto the ceiling, when Pops walks into the room, chasing a balloon, making the mattress fall onto Pops sending him to the hospital. Muscle Man vows to never to prank ever again because his prank almost killed Pops. Rigby is relieved that Muscle Man's prank days are over. Benson tells them of a time where Muscle Man's pranks helped save the park from a rival park's pranks. The rival park decides to prank/invade the park. Benson tries to convince Muscle Man to prank again, but Muscle Man reminds them he almost killed Pops. After seeing the park under siege and Pops being hit in the eye by a punching glove while visiting him in a wheelchair, Muscle Man decides to help the park and start to prank again. The rival park's leader promises that they will never again prank the park, and that his staff will clean up the park. While bringing Pops back to the Hospital it is revealed that Benson used a successful plan to get Muscle Man back into making pranks. The plan was that Pops would open up a present while visiting Muscle Man, claiming it is from the rival park, and would get hit in the eye, causing Muscle Man to save the park.

Guest voices: Kurtwood Smith as Gene the Vending Machine