The
emoticon can be called using the code (?), and only an extremely small group of MSN Messenger users has no idea what it's about, but here we go.
As you can see it includes a question mark and the letters A S L. It represents the most basic and typical opening question ("asl?") in an online chat environment and is an acronyom for asking about your AGE, SEX (gender would be more political correct) and LOCATION. A standard answer from a 17 year-old male from California would be: 17/m/CA.
SIDE-NOTE: If you know sign language then you're aware ASL stands for American Sign Language. A Messer called mikul4u told us he knows many deaf people use this symbol as a way of asking others if they 'spoke' ASL. If they did, that would be the time of firing up those webcams in MSN Messenger!
UPDATE: As of MSN Messenger 7.0.0604 this emoticon has been replaced by the goat emoticon.