Adventure Time Cameo
This easter egg is found in Season 8, Episode 9 titled "Leela and the Genestalk".
During the scene in the tower after Bender rides down the stairs he encounters a chained up Finn and Jake from the Cartoon Network show, Adventure Time. After approaching them Jake asks Bender, “What time is it?” to which Bender replies, “Time for you to shut up!”.
What makes this funny is that both Bender and Jake are voiced by John DiMaggio, which means he’s essentially talking to himself.