Sadface

[Jessica]

the frowning emoticon
a verbal expression of disappointment

[Sonia]

An adjective used to express sadness, annoyance, dissapiontment or mild anger. Sadface as well as [Angryface], [Happyface] etc. can be/is used to replace an emoticon
sadface replaces
Any emotion followed by -face can be used to decribe how youre feeling.

[Hina Muqadas]

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 persons unhappiness. If used in real life, use is generally always sarcastic.