I couldn't help but totally agree with Total Film's latest chart - the 34 Greatest Cult Movies of All Time (see full list here) - "Big Lebowski" IS The Main Cult Movie. And that despite the fact that "Shawshank Redemption" is "officially" my personal favorite and, thankfully, it was also on the list. As well as my second favorite from Coen Bro's filmography - "Barton Fink" ("Between heaven and hell there is always hollywood..." - is my fav tagline). And "Clerks" and "Brazil" are deserving of the Cult title each in their own right.
"Plan 9 From Outer Space" and "Showgirls" are likewise icons - they are just so bad, that you can't help loving them all the more for it. And of course "Freaks" is simply unique as the kind of film that can never be made again.
I've only one question - what's with "Mamma Mia?" Yeah its kinda bad too, but not bad enough to make much of a difference. Yeah there are some pleasing performances, but it's essentially an all-commercial venture exploiting ABBA's musical heritage in such a foul manner that makes you wanna start throwing things at the screen. All because the majority of actors singing in the movie shouldn't be allowed to ever sing - even in the shower.