National Lampoon’s sophomoric spin on The Ladykillers (the 1955 classic starring Sir Alex Guinness) was put on the shelf — probably in response to the Coen brothers’ more earnest redux with Tom Hanks earlier this year — and got a title change. Neither decision can stave off the inevitable: this is a lowbrow, low-budget homage to the Farrelly brothers — and a pretty poor one at that. In tony Southern California, two septuagenarian spinsters fart, parade around in risqué negligées, and make it with two twentysomething nimrods who’ve hatched a plan to marry the rich-and-ready-for-the-grave bats and collect their fortune. But the Mundt sisters (Mary Hartman, Mary Hartman veterans Louise Lasser and Renée Taylor) are neither rich nor decrepit, and in fact, they’ve taken in Calvin and Leonard (Will Friedle and Chris Owen) in order to off them for the insurance money. Director Gary Preisler’s sense of comic timing yields nothing but stilted, humorless moments; even Playboy playmate Nikki Ziering as scantily clad erection bait can’t give the flick a rise. If you’re desperate to see a young lad cavorting with a woman three times his age, rent Harold and Maude. (87 minutes)