An acronym in which commenters on MLIA have an infinite amount of definitions. If you ask what it means, be prepared for all the answers you will receive.
Person 1: Do you know what OP means?
Person 2: Yeah, it's Orgasmic Platypus.
Person 3: No, it's OctoPie.
Person 4: Really, it's Original Poster.
Persons 2+3: No, they're just trying to screw with you. Believe us, not them.