LOW-KEY BRIT FUNNYMAN PUSHES COMIC ENVELOPE By FRANK SCHECK May 21, 2007 -- SEE if you find any of these topics ripe for comedy: the Holocaust; children with cancer; AIDS; Anne Frank; Stephen Hawking; Nelson Mandela; autism; the Cambodian killing fields; pedophilia; bestiality.If your answer was no, then you haven't seen Ricky Gervais, the British actor/writer best known for his two television series: the original British version of "The Office" and "Extras," recently seen on HBO.Gervais, who made his U.S. stand-up comedy debut Saturday night at the newly renamed WaMu Theater (formerly the Theater at Madison Square Garden) as part of the High Line Festival, managed to talk about even the most politically incorrect subjects in a manner that was somehow both offensive and sweet, and always totally hilarious.The comic was introduced to the sellout crowd by the curator of the festival, David Bowie, who sang the hilarious "Chubby Little Loser" ditty that he performed on "Extras."Gervais, dressed in a T-shirt and jeans, delivered a 70-minute set that at once celebrated and mocked his celebrity status. Referring to the recent description of him in a British tabloid as a "chubby funster," for instance, he complained, "That's a gay porn star!"The comedian's relaxed conversational style perfectly suits the quietly brilliant nature of his observations, which are delivered throwaway style. He practically mutters under his breath while pointing out that the Vietnam War had "the best soundtrack" or that Mandela's Nobel Prize "shows you that prison does work."His perfect timing makes hilarious such routines as his depiction of a conversation between Hitler and Nietzsche, while his gift for subtle physical comedy is well displayed in a routine involving a swimming elephant.He's also riotously funny off the cuff, as was made evident by his lengthy comic riffing after an audience member yawned loudly during a routine.Not all of the material worked perfectly, and the massiveness of the venue didn't really suit the brevity and simplicity of the show. But there's no doubt that Gervais has entered the current comedy pantheon.