It was billed on Facebook as a “Night of Mayhem” at “FDR’s Polio Poolhouse.” Gov. Paterson‘s stepdaughter, Ashley Dennis, and about 50 other college kids are likely to be on hand at the governor’s mansion late tonight with “yummy Jell-O shots” and “some beers,” according to the posting. “Come to the governor’s mansion pool house,” it said. “Will be tons of fun . . . So let’s just have a good time and dance in FDR’s honor. The New Deal was AWESOME!” But while a spokesman for Paterson conceded that announcement was put up by a friend of 21-year-old Ashley, a senior at Ithaca College, he insisted the posting “was simply a joke . . . There’s no party or anything at the mansion, there’s no party scheduled,” said Peter Kauffmann. However, a source familiar with the gathering insisted that the party had indeed been planned and was canceled because of an inquiry from Post State Editor Fredric U. Dicker.