The Flabby Patty Shack is a dining place that is a competitor to the Krusty Krab. It only appears in the episode "The Other Patty."
The outside of the Flabby Patty shack is very small. It is made with many wood planks and has a metal roof with a chimney. It features a window in the front, which allows customers to order and get their food, and a door on the side of the building, leading into the kitchen. It also has a large sign that resembles a Flabby Patty and reads "Flabby Patty" in red text.
The inside of the Flabby Patty shack is very tight and cramped. There is a kitchen in the back, where the Flabby Patties are made.
The restaurant is revealed to really be a trick by SpongeBob to get Plankton and Mr. Krabs to work together in hopes that they would be friends again. It might have been demolished or shut down after the events of the episode, as it is never seen or mentioned again.