As much of a nightmare as the actual 'Hangover' movie was (just imagining the headache kind of made us want to die), it makes sense that it could be easily re-cut into a horror film.

Here's a trailer that does just that, and succeeds. Because it turns out if you take away the outrageous jokes, a group of people being drugged and losing one of their friends is actually kind of scary. Also, Zach Galifianakis is only a few steps away from psycho killer at any given moment. Well done.