A 9/11 joke didn’t go down well during a showing of new movie “Ted” attended by former mayor Rudy Giuliani and wife Judith in the Hamptons on Sunday night. The audience at UA Southampton 4 theatres first realized Hizzoner was in the house when there was “a technical glitch about 10 minutes into the movie. The lights came up, and everyone saw Rudy was there.” We’re told they soon got the film running again, and the audience was in stitches at most of the raunchy humor in the Mark Wahlberg R-rated comedy. But one joke in Seth MacFarlane’s potty-mouthed opus didn’t land. In one scene, Ted — the misanthropic CGI teddy bear in the film — asks singer Norah Jones about her nationality, then shockingly spits back, “Whatever. Thanks for 9/11.” “No one in the theater laughed,” the Hamptons spy said. “The joke fell completely flat.” They added the audience “had too much respect for the mayor” to make light of the disaster. But Rudy and Judi were later seen enjoying the rest of their night in the Hamptons.