Eraserhead, hands down. Having watched it three times (maybe more), once drug-influenced, twice(maybe more) not. My wife and I have a look that we send each other at certain unexplainable, un-understandable events that take place in our life together; the origin of this look is the first time we watched Eraserhead; a look that is befuddled, bemused and totally confused. Maybe one more time(maybe more) and I'll get it.
Most of David Lynch, most of John Waters, especially "Pink Flamingos"(actually watched it all the way through). "The Day of the Triffids"...I know I'm mixing weird movies that didn't work with ones that did, but just thinking about Eraserhead has me re-be-fuddled. "Memento" weird but good. Another vote for "Frogs"-reeeeallly bad! "The Incredible Two-Headed Monster", and "The Thing With Two Heads" (one with Casey Kasem the other with Rosie Greer), "The Brain That Wouldn't Die"...O.k. sci-fi is supposed to be weird, I agree...and there does seem to be a history of 'meant-to-be-bad' sci-fi movies, so....maybe more later pbb