"Do or Diaper" is a Season 4 episode of Regular Show (often listed as episode 15 or 16) where Muscle Man bets that Mordecai must wear a diaper if he fails to kiss Margaret by Friday. Critics noted the episode successfully balances the awkwardness of the premise with the characters' intense personal stakes. Read a full review at The A.V. Club .
Watch Regular Show Season 4, Episode 16: Do or Diaper - Now TV [S4E16] Do or Diaper