Joan Rivers wants people to know there are no rules when it comes to fashion. “Anyone who takes it seriously is a fool,” the “Fashion Police” star said during a Q&A for Internet Week at Metropolitan Pavilion the other day. “Anna Wintour, just take your broom and stick it up your a–,” she added. The comedian, who filled in for Johnny Carson before having a falling out with the talk-show host, thinks that Jimmy Fallon will do great when he takes over “The Tonight Show.” “Jimmy Fallon has everything Carson had,” she said. “Carson, till the day he died, was a son of a [bleep] and a drunk — this is off-stage — but onstage you couldn’t touch him . . . He was a fan and excited to do the show, and he was happy he could interview you. And Jimmy has that same thing . . . It’s very infectious.” Rivers, who has more than a million Twitter followers, discussed being on the cutting edge of tech, explaining she gave Prince Charles a Kindle five years ago when it first came out. “He looked at it and said, ‘I’ll give it to Harry,’ ” she laughed.