It Isn't a Rumor. Some Restaurants Have Secret Menus - Yahoo! Finance

Some people insist you can order a McDonald's Monster Mac burger, which has eight patties, and Burger King apparently has an unofficial one aptly named Suicide Burger, consisting of four beef patties, four slices of cheese, bacon and special sauce.

Chipotle Mexican Grill has gained press lately for its Quesarito. It isn't on the menu, but if you ask for it, you can reportedly get a 1,500-plus calorie burrito wrapped in a quesadilla for about $10.

And according to TheDailyMeal.com, Starbucks has at least 12 drinks on a secret menu, including the Cap'n Crunch Berries Frappuccino, which is a Strawberries & Creme Frappuccino with hazelnut syrup (fans of the drink say it tastes a lot like the cereal). The website StarbucksSecretMenu.net indicates that Starbucks offers even more drinks than a customer in the know can ask for.

But by far, the restaurant most famous for its secret menu is In-N-Out Burger, a chain of burger joints in the western U.S. The company has posted its secret menu online, but not all of it, since its website says, "Here are some of the most popular items on our not-so-secret menu." (Note the word "some." We're on to you, In-N-Out Burger.)

Panera Bread's secret, or hidden, menu debuted in January and features six "power foods," which have lean proteins, complex carbohydrates and vegetables, and names like the Power Steak Lettuce Wrap and the Power Chicken Hummus Bowl. These items aren't on the menu in Panera Bread restaurants, but as Davis says, it isn't exactly a secret. Customers who follow the restaurant on social media channels will learn all about them.