It's difficult to give an example of something that's sound-based, but I'd have to liken it to someone being forcibly anal raped, only they're just very unhappy about something.
"UGH!" "OH GOD!" "ARGH!" "FUUUUUCK!" and "FUCK ME!!" are all possible examples of an angergasm.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi