Weirdest movie ever? If we are talking commercial releases (theater releases) it has to be The Forbidden Zone.
http://www.youtube.com/watch?v=l3Uh-AFFDys
http://www.youtube.com/watch?v=WfAP4BCySOo
http://www.youtube.com/watch?v=88tJX6Ru3ew
I love this film.
Pink Flamingos comes in a close second. That is saying a lot since Pink Flamingos featured full figured transvestite Divine graphically blowing her on screen son then eating fresh dog shit. Also, there is a sex scene involving a chicken.
Part of the promotional campaign included handing out barf bags.