Chummy Joes are a type of food sold at the Chum Bucket. They are a parody of Sloppy Joes, a sandwich comprised of ground meat and sauce on a bun, but instead Chummy Joes have chum on a bun. They only appear in the episode "Mermaid Man vs. SpongeBob."
Chummy Joes are two sesame seed buns with chum inside the buns. The way the chum is put in the buns makes it look messy, which is very similar to Sloppy Joes.
In Bob Esponja Calça Quadrada (the Brazilian dubbing), Chummy Joes are called "Lixoburgers" ("Junkburgers" in English), since the Chum Bucket is called "Balde de Lixo" ("Junk Bucket") and the food (along with the restaurant) is hazardous to eat.
In the Greek dubbing, Chummy Joes do not have a name because Plankton's line wasn't "Hey everyone, I made Chummy Joes" but in the Greek dub it was "Hey everyone, I have something for ya," so their Greek name is unknown.
Ironically, Plankton's customers left before anyone digested the Chummy Joes.