Mike & Matt's, at 12th and Mifflin, is the kind of place you hope to find when you move to a neighborhood like South Philadelphia. There it is, amid all the hipsters and craft beer: a little deli, a hundred years old, owned by Mike, 45, and his younger brother Matt, 43, who save their fire for each other. At Mike & Matt's, there's a long-established cast of characters and the nicknames that go with them.