...the Anti-Social Application - created to promote the upcoming movie “How to Lose Friends and Alienate People” - lets you insult them.

Specifically, you can throw insults at your friends, send them a crappy gift, doodle mustaches (or worse) on their photos, and cheat at Scrabble. 

....

http://mashable.com/2008/09/23/lose-friends-facebook/

Via: NMT