Jackie Mason admits that the most famous thing he ever did was to be caught with one of his fingers pointing upwards on the _Ed Sullivan Show_. "The most famous and the least helpful," he says of the 1964 incident. "At that time there was a great wave of excitement about my type of character, because I was new and fresh and different. In those days, every comedian talked like an American; nobody talked like a Jew or a Puerto Rican or an Italian. ... There was a lot of heat to give me my own series, but all the offers were canceled after that incident." Asked whether he actually did make an obscene gesture, the short, stocky comedian with the broad New York Jewish accent shakes his curly head. "The truth is that I didn't -- because I wouldn't be ashamed to tell you if I did. There's nothing wrong with it today. But the truth is that I was making with my fingers -- I have a very visual act, you know -- and Sullivan got panicky because President Johnson had just cut into the program, and when the camera came back on me, it looked like I was giving him some kind of message. The next day, I became headlines all over the world. ... I maintained enough success and enough imagery to be able to do all the other shows as a guest, but the sponsors were afraid to be associated with me as the star." Jackie is telling me this in his dressing room at Dangerfield's (1118 First Avenue), where he's performing six nights a week until December 17. The affable Mason is quick to defend his caustic brand of ethnic humor. "I don't see how it can be harmful. If people do feel any prejudice, it provides an outlet for them to be able to laugh at it. The people who decry ethnic humor are afraid of their own prejudice. You remind them of the ridiculous nature of prejudice. ... Most of the things I say are universal: they're about marriage, about minorities, about social problems -- the issues of the day." He also pokes fun at doctors, weathermen and every profession in between. Then there are his highly exaggerated impressions of Menachem Begin, Jimmy Carter and Ed Sullivan ("He always asked me to do an impression of him on his show. He found out from me how to do _him_."). Another of his ploys is to razz the audience members. "In 21 years," he said, "I only had one incident where a guy got mad and wanted to punch me in the mouth. Thank God I move very fast. He wanted to kill me. Obviously he didn't catch me. That's why I'm still here for the interview." Born in Sheboygan, Wisconsin, he was raised in New York's Lower East Side from the age of 5. Following in the footsteps of three older brothers, he studied to become a rabbi to please his father. "I knew it wasn't for me. I have all license to be a rabbi, but I'm not a rabbi." A bachelor and Eastside resident, he loves New York because "this is a melting pot that doesn't really melt. There's a pot, but it's full of unmelted people."