Jeffrey the Jellyfish only appears in the episode "I'm Your Biggest Fanatic." Patrick chases him to touch him. At the end of the episode, Patrick has him tied up in a wagon.
Jeffrey is a large, pink jellyfish. Instead of normal stingers, he has legs, and they also have knees, as shown when they are bent over while Patrick carries him in a little wagon.
- The security guard who keeps telling Patrick not to touch, probably doesn't catch Patrick at the end of the episode, since SpongeBob and Patrick are seen leaving with Jeffrey.
- Jeffrey is either a jellyfish that is not regular and sentient, or he is just a fish in a disguise. If he is a jellyfish, it would be impossible for him to walk on legs.