Russ Meyer's Beyond the Valley of the Dolls (1970) is a kind of even-more druggy The Monkees with breasts, in which a young female band (The Kelly Affair, later renamed The Carrie Nations) taste the decadent delights of Los Angeles only to be caught up in Manson-murder style slaughter.
It features a couple of classic party scenes, set at the mansion of Ronnie Barzall, a Phil Spector-like music manager. People dance energetically to a show by psychedelic band the Strawberry Alarm Clock . It's all gyrating hips, hands in the air, a smattering of semi-naked dancers amongst the swingers and groovy people, sex and drugs in beds and swimming pools in adjoining rooms. It's not a hippy crowd as such, more a mixture of freaks and suit-clad jet set. Best of all is the dialogue: "This is my happening and it freaks me out!", "In a scene like this you get a contact-high!" and the ultimate chat up line "you're a groovy boy, I'd like to strap you on some time".
There's also a bit where a woman on a chain says "What I see is beyond your dreaming", a line I immediately recognised as a sample and thanks to Dissensus now know to have been used on Roni Size's Mad Cat from the New Forms album (1997). Lots of trailers and clips from the film here.