At the height of their fame, the Monkees teamed up with Jack Nicholson to film the psychedelic classic Head – and destroy their careers in the process.

These days, it is fondly remembered as one of the weirdest and best rock movies ever made, and a harbinger of the so-called New Hollywood. Quentin Tarantino and Edgar Wright are both fans. DJ Shadow and Saint Etienne have sampled its dialogue. According to director Bob Rafelson, the Beatles and the Rolling Stones both requested private screenings, while Thomas Pynchon attended a screening disguised as a plumber.
http://www.guardian.co.uk/music/2011/apr/28/monkees-head-jack-nicholson-interview