Tucker (Alan Tudyk, Firefly) and Dale (Tyler Labine, Reaper) are backwoods American hillbillies -- just ignore Dale's trucker cap with the Canadian slang "give'r" written on it -- peacefully minding their own business at their broken-down mountain vacation home, a shack they're too dim to notice is decorated with evidence of a mass murder. They're best friends, fishing buddies and constant companions, this close to feeling like what would have happened if Jake Gyllenhaal and Heath Ledger had been granted their dream of a home on the range.
Into this redneck paradise comes a crew of obnoxious college students, weaned on horror movies and determined to find the worst in the grimy yet sweet-natured locals. When extremely shy Dale tries to strike up a conversation with Allison (30 Rock's Katrina Bowden), one of the girls in the group, the terrified students assume he's stalking her. Later, when Allison falls into a lake and is rescued by Tucker and Dale, they assume she's being kidnapped and that they're all going to be killed next.
What follows is Texas Chainsaw Massacre and Wrong Turn and every other hicks-as-psychotic-murderers film turned upside-down and played for the laughs that were always there, waiting patiently to be teased out from under a shallow grave of cliches. As the hysteria-blasted kids find increasingly gory ways to accidentally kill themselves and each other, Tucker and Dale get more and more freaked out and more willing to commit violence themselves, not only to save their own lives but also to protect the injured Allison.
Is it as insanely gory or brutally funny as Piranha 3D? No, but it doesn't miss that mark by much. This is an extremely bloody, extremely funny shock-comedy that succeeds at doing exactly what another Scream sequel couldn't, slaying a fresh set of horror tropes and rehabilitating the horror-comedy genre for a new generation of people who don't see anything wrong with laughing at a teenager mangled by a woodchipper.
Just don't leave the theater thinking that loner hicks in isolated murder-shacks are all misunderstood softies who just want to play board games and enjoy beer responsibly. In real life those Deliverance-y guys are always the ones with bodies buried under the floorboards. The cliches exist for a reason.