What are some secret menu items at In-N-Out Burger?

Items on the so-called secret menu at In-N-Out Burger include burgers with additional patties of beef, grilled cheese, and protein-style and animal-style burgers. Customers can add up to three patties to a burger for a double-meat, 3 x 3 or 4 x 4 burger.

Customers can order a hamburger without the meat for a grilled cheese or without the bun for a lettuce-wrapped protein-style burger. The animal-style burger has added pickle, extra spread and grilled onions.

Secret menu items are items that combine or alter advertised menu options to create new dishes. In-N-Out encourages customers to do so and has trademarked the names of several of its off-menu items.