Most people know about animal-style burgers and fries, even the odd "Protein-style" (using lettuce instead of buns), but did you know about... The Flying Dutchman is basically a 2X2 (two patties, two cheese slices) with out the bun and sauce. The Root Beer Float is supposedly a very pleasant surprise to many -- try it if you're on the West Coast right now!
Two relatively less known secret menus at In-and-Out Burger - The Flying Dutchman & the Root Beer Float
@miranpark88 that's a good question. I can't find anything online so I've asked around... the best answer I got: the "flying dutchman" is a ghost ship that can't dock at any port, so the meat is the flying dutchman and the bun is the metaphorical dock....Does that make sense? lol