It may be a classic diner in a hip nabe, but that doesn’t make the Square a square. Have a meal here and you’ll want to use ’50s slang, too. Plop down in a comfy booth, order a burger or an omelet with an egg cream—or, if you insist on sticking to that diet, a wrap—and marvel at prices that will make you wonder if you accidentally received a menu from the age of the Fonz.