An emoticon or "smily" which is used on a message board to show others that your post was sarcastic. Also referred to as jimlad. Popularized by SeattleClone, a member Cyclone Fanatic (a well-known message board for fans of Iowa State University).
Picture shown here-
Poster 1: I hope Harrison Barnes doesn't come here!
Poster 2: I hope you meant to put a sarcasm pirate on that because if you didn't, you are an idiot!