In-N-Out's Secret Menu Has Huge Milkshakes (And You'll Need An Extra Cup)

In-N-Out's official menu is as basic as it gets. There are only three burgers — a cheeseburger, a hamburger, and a double double, which is essentially a double cheeseburger — as well as fries, then milkshakes available in the standard chocolate, vanilla, and strawberry flavors. Sometimes simple is better, and many customers do order from this selection. However, the chain's secret menu is just as popular.

The version of In-N-Out's secret menu now listed on its website provides six extra options, allowing you to order your burger with double the meat (but not double the cheese), triple the meat, or quadruple the meat. You may also order it protein style, replacing the buns with lettuce, or animal style, which includes a mustard-cooked beef patty topped with extra sauce and grilled onions. Other than the different burger styles, In-N-Out also lists grilled cheese; however, the website makes no mention of animal style fries or any secret menu milkshakes.

In-N-Out has a secret milkshake size

While In-N-Out has four sizes for soft drinks listed on its official menu, it only displays one set price for its milkshakes, leaving customers to assume that they only come in a single standard size — 15 ounces, per the site's nutrition facts. As it turns out, In-N-Out's secret menu has large and extra large milkshakes.

The extra large milkshake is double the size of the normal one, coming in at about 30 ounces, while a large soft drink cup holds 22 ounces. Despite the extra large being a much bigger milkshake, TikToker @hellthyjunkfood shared that it costs only a fraction of the price more, though the actual dollar amount depends on the In-N-Out location you go to. If you're planning to order two milkshakes anyway, @hellthyjunkfood recommends ordering the extra large and asking for a second cup to split it. You'll end up getting the same amount of milkshake as you would if you were to order two regulars, but at a cheaper price.

This isn't the only secret menu milkshake

As if extra large shakes weren't enough, In-N-Out also has two other milkshake offerings on its secret menu. If you can't decide between vanilla, chocolate, or strawberry, you have the option to order a Neapolitan milkshake, much like a Neapolitan ice cream, which has all three flavors in one cup. There's also a black and white milkshake, made with the chocolate and vanilla flavors (presumably, you could mix strawberry and chocolate or strawberry and vanilla instead). They've reportedly served root beer floats in the past, using the soda mixed with a vanilla milkshake.

You may have heard of something called a "monkey shake" through TikTok, but contrary to popular belief, this isn't one of In-N-Out's secret menu milkshakes. People on the app at one point were claiming that it was In-N-Out's version of an Oreo milkshake. However, a handful of self-identified In-N-Out employees have revealed in the comments section of a viral TikTok that it has never existed, and an In-N-Out fan who tried to order it confirmed this to be true. If you want to order a secret menu milkshake from In-N-Out, just stick to the upgraded sizes and the few extra flavors.