Okay, start the jokes. T a Leoni, 35, has told Canada’s Calgary Sun newspaper that her husband, David Duchovny, 39, has really hit bottom. When it comes to painting, that is. The onetime “X-Files” star uses his rear end instead of a brush, says his spouse. Talk about being cheeky. “David and I recently did some butt painting for a charity auction,” Leoni, who opens in the dino sequel “Jurassic Park III” on July 18, told the paper. She explained their technique, which basically boils down to his taking off his clothes and her applying paint to his buns. Duchovny then squats down on the canvas and really makes an impression. “I call myself the paint loader,” said Leoni. “I apply different colors to his cheeks, and then he sits on the canvas.” Just one coat won’t do, either. “I reload, and he repeats,” she said. “I get to spank him a little to blend the colors,” she added, noting that she defies “anyone to say that David and I don’t know how to have fun.” Bottoms up.