(KTLA) — For a fast-food place with such a simple, basic menu, there is still a lot of mystery surrounding In-N-Out Burger.

The new book “The Ins-N-Outs of In-N-Out Burger: The Inside Story of California’s First Drive-Through and How it Became a Beloved Cultural Icon,” written by the granddaughter of the company’s founder, reveals a few surprises about the fast food chain.

For starters, did you know that Animal Style was inspired by teenagers who used to hang out in the parking lot at night?

At closing, they would come in and request a burger the way the managers were making them special for themselves. Night after night, they would order the same thing and wanted to replicate the unique combination of grilled onions, extra spread and a mustard grilled patty at a different location.

The managers said to just order it “animal style,” based on the nickname for the teens in the lot.

At the end of the book, they detail the chain’s not-so-secret menu, and there are a few that may be unfamiliar to even regular In-N-Out diners. See how many of these you’ve heard of.

Animal Style: a burger with lettuce, tomato and a mustard-cooked patty with pickle, extra spread, and grilled onions.

Flying Dutchman: two slices of cheese melted between two patties. No buns and no veggies. Named after the racing name of founder Harry Snyder; this was his favorite snack according to the book.

Protein Style: a burger wrapped in lettuce instead of a bun.

Tomato Wrap: just like protein style, but the “buns” are tomato slices.

Grilled Cheese: Two slices of melted American cheese, lettuce, tomato and spread on a toasted bun. You can get it with or without onions. There is no patty in this one.

Double Meat: Two patties, lettuce, tomato and spread; with or without onions. A Double Double differs slightly; it has double meat and double cheese.

3×3, also known as a Triple-Triple: Three patties, lettuce, tomato, spread and three slices of cheese with or without onions.

4×4, also known as a Quad-Quad: Four patties, lettuce, tomato, spread and four slices of cheese with or without onions.

There are rumors of 5×5 and up but former employees tell me that 4×4 is officially the max they can go.

Veggie Burger: According to the book, this used to be known as a “Wish Burger” because some customers “wished” there was a beef patty inside, but not so much today. This is two buns filled with lettuce, tomatoes, onions, spread and pickles if you want them. There is no patty of any kind inside.

Other special requests:

You can ask for buns not toasted at all or extra toasted. You can add chopped chilies to your burger or fries and you can ask for extra of pretty much anything: tomatoes, lettuce, onions, or spread.

You can also ask to have your burger cut in half or in quarters (popular with kids!)

Finally, you can ask for your cheese “cold,” which means they don’t melt it on the burger.

As for drinks, you can get a Neapolitan shake, which is a mix of chocolate, vanilla and strawberry all in one cup. There’s even a root beer float, which is a vanilla shake with root beer added on top.

When it comes to fries, you can ask for them well done, which is extra crispy, or even “light,” which is less cooked. There are also cheese fries, which is sort of self-explanatory. Animal Style Fries have the cheese, plus spread and grilled onions.

Apparenty, a lot of people order a meat patty by itself with no salt, which is popular for dogs.

The book is filled with company history, drama and all the little nuances that make In-N-Out what it is today. One warning: you will get very hungry reading it!