The Sandwich only appears in the episode "I ♥ Dancing."
It looks like a submarine sandwich with tomato, lettuce, cheese, it is unknown if it has pepperoni or the patty from the Krabby Patty.
A sandwich can be made with lettuce, tomatoes, pickles, pepperoni, onions, cheese, or other things. On top, there is usually a kind of sauce.
Role in episode
SpongeBob dances in the Krusty Krab with a tray full of Krabby Patties and throws them through the air, which land on the tables of the customers. The sandwich lands on Frankie Billy's table, along with a drink, nachos, a pizza, and a knight's suit of armor. It is unknown if it is on the menu for the Krusty Krab.