When one goes to an In-n-Out Burger, one has the option of ordering extra burger patties and/or extra cheese in one's burger. It's not on the official menu but In-n-Out has all sorts of undocumented ways of modifying one's lunch. Some call it their "secret menu" but it's about as secret as William Shatner's hairpiece.
Their conventional Double-Double has two patties and two pieces of cheese but if you ask for a 4×4, you'll get four of each. A 3×5 is three patties and five pieces of cheese and so on. Recently a group of people went into one outlet and had them prepare a 100×100. See what happened.