when you're hungover as shit after a spending a night drunk as a skunk

An emoticon that is used to portray either laughter or death. For this reason, it is extremely ironic and often creates confusion between texters.

Microsoft windows xp one of the most successful operating systems to date

An emoticon that signifies "laughing really hard while sticking out the tongue."

See also: XD

An abbreviation for 'experience' in the context of role playing games, usually given in a point value and used to determine a character's level.

1) An emoticon, with ones eyes crossed and tongue sticking out. Obviously this means "retarded."
2) The most recent edition of the Windows OS, recognizable by the GUI that looks like it was made by Playskool, and the code that was probably written by same. The OS was named for said emoticon.
3) Short for Experience in many RPGS. Variant of EXP.