First appearing in the episode “The Day the Earth Stood Stupid,” the Hypnotoad is one of the funnier running gags on “Futurama,” with the showrunner loving it so much that he included an episode of “Everybody Loves Hypnotoad” on one of the show’s DVDs. In an interview, the designer of Hypnotoad, Mark Ervin, revealed its design was a nod to an episode of “The Simpsons.”