Stepping into the O’Sullivan Cigars shop is much like stepping into a cigar box. It’s small, smells good, and is crowded with like-minded friends. Tom O’Sullivan opened the humidor seven years ago, back when cigars and dot-coms were all the rage. But after many stogie emporiums collapsed, O’Sullivan has survived thanks to his prime selection. “A rep came in here the other day and gave me a bag of his cigars,” he said recently. “Garbage. All of ’em. I smoked one, threw ’em away.” Sullivan’s loyal and erudite customers come back not only for the tobacco, but also for the Brooklyn native’s charming bull sessions. If you drop by, ask him about the time he played lead guitar with the Ramones at the Warfield. Or just light one up and chill.