Once upon a time there were only two — yes, two — bars on all of Avenue B: 7B and Mona’s. The avenue has changed a lot, but Mona’s hasn’t: It’s still full of punks, Irishmen, and college dropouts, plus a pool table, jukebox, and weekly bluegrass and jazz. And it still features the same lack of décor — an ancient bar and a few faded posters in the front room. And don’t order a cosmopolitan at this no-frills drinking establishment. Oh, they probably make ‘em, but do you really want to be on the receiving end of that many dirty looks?