If your avatar is someone iconic or well-known, there may be a chance that someone may take offense. However, I personally do not see an issue, though I would not take my sole word for it. Until one of the staff contacts you about it, I believe you are fine.
I was running into school, because I stayed up late to do a project. When I ran through the door, my shoelace got caught on the frame and I fell like an idiot and broke my project.
Honestly, this site's spoiled me. I've grown accustomed to people respecting and honoring opinions here, and it really shocked me on places like Memecenter, where opinions go to die.