It is a burger that contains a burrito in between two sesame-seed buns.
Role in episode
SpongeBob makes this patty during his time as a fry cook at Taco Sombrero. Señor Taco likes it, but after his taste tester chomps the Burrito Patty, it sprays its filling in the faces of two bystanders. He then fires SpongeBob.
Later in the episode, Señor Taco is among the restaurant owners who fight for SpongeBob because his customers apparently liked the Burrito Patties.