The reason for that security question is to prevent others from getting access to your password and email account.
If old school friends, or relatives, cannot tell you what your childhood nickname was, then all I can suggest is you contact AIM Help Desk. This may help;
My laptop was recently infected by a keylogger. I use AIM mail for my main email account, and I'm having trouble getting the password reset. My security question was "What's your childhood nickname?" I tried everything I could think of, however I made this e-mail several years ago and don't remember what I wrote down.
There is an option of resetting your security question, but you can only do that if you know your password.
Now my account is locked and I can't do anything.