The opening scene of "Dallas Buyers Club" shows Rod Woodruff having sex with a woman who we later learn has a lot of needle marks in her arm. There appears to be a third person in this scene and it's unclear whether they are male or female and whether they are involved in the sex.
It looks like a dude doing Ron from the rear while Ron is doing a woman! You see many guys being homophobic while being bisexual themselves, so it fits. (Though you never see Ron with any other guys in the movie, and yes, he flashes back to some girl and her I.V. tracks, so my first statement is probably not the case).