It is a Krabby Patty with triple the amount of ingredients. Squidward orders one on a kelp bun with extra sea pickles and demands SpongeBob to "burn it to a crisp."
Role in episode
Squidward realizes that he actually likes Krabby Patties, so he orders a Triple Krabby Supreme, but since he does not want SpongeBob noticing that his secret, he lets the "customer"'s identity remain unknown. After SpongeBob finishes cooking it, he asks who ordered a Triple Krabby Supreme, but receives no answer, so he immediately eats the burger to prevent its deterioration, much to Squidward's disappointment.