In-N-Out is a Bay Area fast food favorite. The menu consists of only six items: the hamburger, cheeseburger, double double, shake, fries and fountain drinks. But that doesn’t begin to describe the offerings.

Popular teen picks on the secret menu include animal fries, animal-style burgers, protein-style burgers, “meat x cheese” combos and Neapolitan shakes.

Animal Fries start with In-N-Out french fries, then add grilled onions, melted cheese and In-N-Out special sauce.

The animal-style feature is not limited to fries.

Animal-style burgers are fried with mustard and topped with grilled onions, melted cheese and more spread. Even if the burger is more expensive than the original, animal-style burgers are popular and delicious enough to keep people wanting more.

The protein-style burger is the same as regular hamburgers except that it’s enclosed in two large pieces of lettuce instead of a bun – just right for people on low- to no-carbohydrate diets.

"My mom usually gets this because it isn't as fat as other burgers," says Leah Defigueiredo, a student at Hercules High School.

Other secret menu selections include much more meat.

Combinations of meats and cheeses, which go by the formula MxC, are very popular. A 2x4 would be two meats and four cheeses, while a 3x3 would be three meats with three cheeses.

The In-N-Out in Pinole will create a maximum of a 4x4, but there are reports of combos up to a 100x100. With the increase in size comes an increase in price.

The Neapolitan shake is an In-N-Out favorite, created from swirls of chocolate, strawberry and vanilla shakes.

The “secret menu” is actually not so secret, partly due to word of mouth, and partly due to multiple blogs and websites.