Joe Sykes and Drew Moerlein in V/H/S (2012)
23 minutes in the movie, Joe Sykes gets naked at a motel. For the next few minutes we see him naked, and although the camera is shaking a lot, we see his butt and uncut dick.
66 minutes in the movie, Drew Moerlein is undressing to go swim in a lake. We only see his butt.