Talk about false advertising: “Scary Movie’s” original tagline promised “No Mercy. No Shame. No Sequel.” No problem — Memory is short and profits are potentially steep (the original reaped $260 million at the box office). “Scary Movie 2” returns with a whole new set of jokes and a potentially lethal returning cast and crew — including Marlon and Shawn Wayans and Anna Faris in front of the camera and Keenan Ivory Wayans behind it. The first took aim at teen horror flicks; this spoof targets classic horror movies. We’ll have to wait to see if “Rocky Horror” qualifies, although with Tim Curry on the roster, anything’s possible.