Go ahead and be moody. Whatever mood you want. In fact, make your own custom Emotions. Here's how:

1. Click your Windows Start button, select Find or Search, then Files or Folders.
2. A new window will launch allowing you to search for files on your computer.
3. Type emote_user.dat in the Named: field and click the Find Now or Search Now button.
4. When the file is found, double-click it.
5. If you're asked which program you'd like to open the file with, choose Notepad.
6. Once the file is open, add new emotes in the format mentioned at the top of the file.
7. Close the file and make sure to save the changes.
8. Restart Messenger and emote away!