25 Days of Gays: Bite Marks (2011)

Bite Marks is a horror comedy from writer/director Mark Bessenger. It centers around Cary (played by Windham Beacham) and Vogel (played by David Alanson), a couple exploring the outdoors in an effort to strengthen their relationship. They cross paths with Brewster (played by Benjamin Lutz), a truck driver who steps in to take on his brother's route, unaware that he's transporting coffins carrying blood-thirsty vampires. The trio must face the threat, while trying to salvage their relationship and work through Brewster's sexual confusion. Benjamin opens the movie with a rear nude scene. David gets multiple rear nude scenes as Brewster spies Vogel & Cary having sex in a bathroom stall, and later when he moons a camera.