IN N OUT DISALLOWS LARGER THAN 4 BY FOUR
There are, however, additional named items not on the menu, but available at every In-N-Out. These variations reside on the chain's "secret menu," though the menu is accessible on the company's web site. These variations include 3x3 (which has three patties and three slices of cheese), 4x4 (four patties and four slices of cheese), Neapolitan shakes, grilled cheese sandwich (consists of the same ingredients as the burgers except the meat, plus two slices of melted cheese), Protein style (wrap with lettuce; consists of the same ingredients as the burgers except buns), and Animal Style. Both Protein and Animal Style are house specialties that the company has trademarked because of their association with the chain. Animal Style fries come with two slices of melted cheese, spread, and grilled onions on top. Animal style burgers are cooked in a thin layer of mustard, and in addition to the lettuce and tomato it also includes pickles, grilled onions, and extra spread. Whole or sliced chili peppers are also available by request.
Until 2004 In-N-Out accommodated burger orders of any size by adding patties and slices of cheese at an additional cost. A particularly famous incident involving a 100x100 (100 patties, 100 slices of cheese) occurred in 2004. Once word got out of the massive sandwich, In-N-Out management disallowed anything larger than a 4x4. One can also order what is called a "Flying Dutchman" which consists of two meat patties and two slices of cheese by itself (no bun, condiments, or vegetables).