You may prefer the classic chocolate, vanilla, or strawberry flavors when ordering an In-N-Out milkshake, but you may not have to choose between the three delicious treats. Thankfully, there's a secret In-N-Out milkshake that allows you to combine all three flavors.

In-N-Out has a "secret menu" that allows in-the-know customers access to some unique creations, including the Neapolitan milkshake that combines all three milkshake flavors into one. This can also be applied if you're wanting just two of the flavors such as chocolate-vanilla, chocolate-strawberry, or vanilla-strawberry.

There are even more secret drinks and treats on the In-N-Out secret menu, like a root beer float, 4x4 burgers, or a Scooby Snack patty for your furry friend. If you love iced tea and In-N-Out's pink lemonade, there's an Arnold Palmer or "Tea Ade" that mixes the two for a delicious treat.