When straight guy is looking at porn, he looks for a good picture to masturbate to. Once he finds a good picture(of a girl), he starts doing his business in front of the computer. But if just as hes about to release his stream of protein, possibly into a tissue or (in rarer cases) the wall, A popup with a guy spread his asshole thirteen inches appears just as his unfortunate sperm exits his body. There is usually shock, pain, and humiliation as the man has just became.... another victim of accidental homosexuality.
"Dude! I was a victim of accidental homosexuality last night."