In-N-Out already has a cult following, but the people who really love the chain know the best orders aren’t usually found on the regular menu. Sure, Animal Style still gets most of the attention, but fans have come up with tons of unofficial combo orders that take things to a whole other level taste-wise. Mustard-fried patties, chopped chiles, well-done fries, extra spread, Neapolitan shakes—half the fun of ordering at In-N-Out is figuring out your perfect combination. The menu itself is pretty simple, which is exactly why all the little customizations stand out. Plus, once you try an In-N-Out menu upgrade, there’s no turning back. After you learn the secret to personalizing your order, you may not want to stick to the basics anymore.…