Futurama Easter Egg - Matt Groening's Secret Surprise

Before The Simpsons and Futurama, Matt Groening made Life in Hell, a comic strip about a tormented one-eared rabbit named Bongo. In episode 17 of Futurama, "X-mas Story" Fry goes to the pet store to buy a gift for Leela. If you look carefully, you can see Bongo being displayed as a pet.