the word used to illustrate unhappiness in MSN convos when no one can be bothered using the emoticon. Also can be said in real life to exaggerate or bring extra attention to a person's unhappiness. If used in real life, use is generally always sarcastic.
Totallypwnagefriend: Hey wat was with ur sadface today?
Well in maths today I pretty much got told to fuck off by the teacher
and I was like 'awww, sadface. I don't care'