Horror movies: You know the drill. Oversexed, nubile, blond teenage girls cavort shamelessly with horny teenage boys until the bad guy murders them -- often with with a phallic weapon and abundant fake blood. Although the boys are in pretty much equal danger of being dead before the final credits, it's almost always the girls who are portrayed as most vulnerable and in need of protection. Why? Well, because girls have vaginas, which puts them at danger of being attacked by the male half of the population. Therefore, we must costume them in the most revealing ways possible, make them aware of their own sexuality, and then punish them for it with death. That way, when we kill the girls off, it'll kind of be their own fault for being such sluts. It's not just horror films, of course; from thrillers to romantic comedies, women are endlessly at the mercy of their vaginas. And therein lies the appeal of Teeth, a different kind of horror film, which just played the Sundance Film Festival.