In the episode A Flight To Remember, Fry, Leela, and Bender came back from some cannibal planet. What was the planet like?
A cannibal planet.
If I remember correctly, there was a joke about Fry & Leela almost getting eaten, so we can assume that it was a cannibal planet of humans (even though we thought Leela was an alien at that point). That's something.
Maybe every time a human is eaten another one somehow appears and everybody on the planet is constantly trying to eat one another. Although, if people are constantly eating each other, who would have time to order a package?