The Chumstick, also referred to as Chum on a Stick, is one of the main chum food items made by Plankton and one of the many chum products sold by the Chum Bucket. They first appear in the episode "Spongicus."
In normal episodes, they are sort of in a shape of a corn dog, but in "Spongicus" they are a rectangle shape on a stick. Both times they are a dark red color but with a different kind of stick on them.
They are known for their disgusting taste and making people vomit. The ingredients to the Chumstick are revealed in the episode "Spongicus."
Chumsticks play their biggest role yet in the episode "Plankton's Regular." Nat Peterson becomes a frequent customer of Plankton's due to his love for them. However, near the end of the episode it is revealed that they actually made him sick and he only pretended to like the food so Plankton would stop complaining about his restaurant's poor business.
In "Chum Bucket Supreme," Plankton feeds one to SpongeBob, which causes the disguise he and Mr. Krabs were hiding in to explode. SpongeBob is then seen wiping his tongue with a kitchen sponge, obviously disliking the taste.