Zoomerang! (1974)

Gary and Jack are longtime companions, yet their daydreams tell another story. In their dreams, Gary sucks and fucks a chiseled Adonis who comes to life, while Jack remembers a psychedelic, 1960's orgy where he deep throated multiple men (and a Marilyn Monroe impersonator) with great gusto. Back in reality, Gary has sex with a close friend of Jack's, which brings out major issues in their relationship.