OK, this is cult. This is scandalous. This is classic. If you haven't seen The Rocky Horror Picture Show (1975, Jim Sharman), drop everything and get a copy!
If you thought that Shortbus (antother must movie for people in SRHR, mind you) was outrageous, this is even better. No graphic sex but an even more whimsical take on sex and sexuality. Gender fluidity, happily (pleasurably!) lost virginities, ditching the monogamy... all that in 1975 and in drag!
In case you saw The Perks of Being a Wallflower and didn't really get the performance part, this movie is what they were mimicking. Being part of the fandom, obviously.
+ The soundtrack is the best. Here, have a taste!