“Slaxx” (*1/2 out of four) was a dumb-and-dumber horror comedy about (get this) a possessed pair of killer jeans who start to systematically kill the staff of a trendy clothing store; it is then up to a feisty young salesclerk (Romane Denis) to stop its bloody rampage before it’s too late. Thin material in the vein of “Attack Of The Killer Tomatoes” lacks scares, laughs, and (most of all) conviction. Even at only an hour-and-17-minutes, film itself is pretty “slack” and weak.