The Nite Owl calls itself the Home of the Jumbo Burger, and there used to be signs posted in the dining room that the Jumbo was “the largest post-war hamburger in the area.” In fact, the Jumbo is not all that huge, but it is a lovely lunch-counter paradigm, just hefty enough to be a modest meal as a single, or a veritable banquet on a bun if you order a Double Jumbo. It comes on a toasted bun and is available either plain or under a heap of fried onions, with or without a mantle of cheese.