An abbreviation of the word "Attention". Most often used in message boards when one user is trying to get the attention of another user.
ATTN: Darklao, someone has stolen your Punchout code!!
ATTN: DeadGhost, LET'S DUEL!!
Air through the nose - An aim term used when someone says something thats funny but not enough to use "lol". When u just blow air out of your nose and smile.
Goldenhoochie134: dude thats like the time you fell down the stairs
Nudekaraoke: attn...ya that was funny