How do you ice yourself in Mafia Wars?

Answer 1

Depending on how specifically mean it:

1. Fight a boss that is too powerful for yourself, and let him kill you.
2. Create another Mafia Wars account (and facebook account) and attack yourself.

Also, in order to lower your health to facilitate either of the above two, you could attack other people or provoke attacks from other people by attacking people way above your level. Another way would be to post on the mafia wars forums asking to be attacked, (or behaving in a way that will get you attacked) though that may be frowned upon.