Chicago's most infamous hot dog stand is famous for roasting customers, yelling insults, and serving up attitude with every order. But regulars know there's one item that's never on the menu: the legendary $20 "Chocolate Milkshake."

Order it, and the entire restaurant goes silent. Moments later, a very enthusiastic woman emerges from the back, delivers the world's most unforgettable "milkshake demonstration," and leaves first-timers questioning everything they thought they knew about Chicago dining.

Tourist trap? Urban legend? Local tradition? There's only one way to find out.