The Ulti-Meatum is the burger seen in "the best burger in the world". It is heard that it only comes every 100 years. It is served from the Grill 'Em Up Truck by its head chef, A.J. Maldonaldo. Only one per customer is allowed.
It is a large burger, cooked into a large burger, with buns. There are layers of cheese and Himalayan Ketchup also inside.
It is made by stuffing a cheeseburger inside a cheeseburger and using two deep fried cheeseburgers as buns. Then the special Himalayan Ketchup is added.
According to Muscle Man, the Ulti-Meatum Idaho Style is where the burger is made the same way but with a whole bag of chips in it as well.
- The name is a reference of the word "ultimatum", which means demanding change.
- At the end of The Best Burger in the World Ajay Maldonaldo says Mordecai and Rigby are lucky because they got the last burgers, but Benson ends up eating both of them, saying that they were right.