By far the weirdest movie I've seen has to be Gummo. The scene with the rednecks arm wrestling in the kitchen was pure gold. Also, the two brothers fist fighting was great, too.
http://en.wikipedia.org/wiki/Gummo
EDIT: Here's a delightful scene for you to feast your peepers on:
http://youtube.com/watch?v=EP_nXPNJ8Fo&feature=related