http://www.geocities.com/postitlord/nicknames/MSNt
aboo.html
On that site is a list of words and word fragments not allowed by MSN (I would have to rate that site only suitable for 15+.) I once tried to have the word "Help" in my name for some reason, and it took a lot of trial and error to discover that was the forbidden word, but I have no idea why. There are plenty of ways to get around MSN's rules, though I don't recommend using them to add swear words to your name (you wouldn't do that, anyway). First, I would try using another letter in place of the "I" ("eye"), such as "l" ("ell"), because they look identical to me. Alternatively, the following symbols could replace letters:
l, |, �, �, �, �, �, �, �, �, �, �
�
'
0, �, �, �, �, �, �, �, �, �, �, �.
(Some of the symbols might not come out on Answerbank.)