PMO meaning slang in slang usually means “Pisses Me Off.” People use it in texts or social media when they feel annoyed or angry about something. For example, someone might say, “It really PMO when people lie,” to show frustration. In some online communities, especially on forums about self-control or habits, PMO can also stand for “Porn, Masturbation, Orgasm,” but the most common casual slang meaning in chats is “Pisses Me Off.”