4. Jess Weixler and Ashley Springer in Teeth (2007)
Every single hookup in writer-director Michael Lichtenstein's disturbing 2007 horror-comedy Teeth qualifies as immensely nauseating, considering that Dawn O'Keefe (played nicely by Jess Weixler) has a rare case of "vagina dentata." And, yes, that means exactly what you're thinking: Her nether regions are packed with chompers.
And, yes again, those private teeth can't help but bite off the joint of any guy who's unfortunate enough to anger her during sex. Which happens more than once in Teeth, but never more sickeningly than the sequence in which Dawn thinks she's bumping uglies with a decent guy, for a change, only to find out that he's just as scummy as the next soon-to-be-dickless fella. See, it pays to be chivalrous.