Usually used in message boards to denote that the statement you have just posted has a sarcastic tone. Comes from HTML code.
Wow, you are the best because you have a high post count./sarcasm
by Porn-O's June 04, 2006
Yes, because you're the only one who knows how this shit works, aren't you /sarcasm
by Gumba Gumba April 05, 2004