Rusty Rickets is a character that appears in the episode "Séance Shméance."
Rusty Rickets is an overweight ghost that is green in color. He wears an apron that is oily, just like most fry cooks have. He also wears a small hat. He seems to talk completely in gibberish, however it is possible that he is foreign to Bikini Bottom or that it is a ghost language.
Rusty Rickets was a former cook at his own restaurant, called Rusty's Rib Eye, where he was infamous for his "Rusty-on-Rye" sandwiches. Even though this sandwich is made from driftwood, spackle, and shellac, this sandwich appears to be very popular, as even Old Man Jenkins loves to eat them. He seems to talk completely in gibberish, however it is possible that he is foreign to Bikini Bottom or that it is a ghost language.
Rusty Rickets is first seen after SpongeBob summoned him by holding a Séance. Rusty agreed to show SpongeBob how to make his Rusty-on-Rye sandwich, but this attracted the other ghosts from the past. It appears that Rusty has become very popular due to his sandwich, and the rest of the ghosts soon started to destroy the Krusty Krab. However, Mr. Krabs eventually came and stopped all of the ghosts, and Rusty wasn't seen again after that.