I have a theory. They say that often times when people get bitten by a shark it is just an 'investigatory' bite. In other words, sharks explore though their mouths. If it seems strange they will give it a bite to try and figure out what it might be.
Similarly, I think chickrens do the same thing. I think they touch their world in the only way they can, by using their beak. I have Barred Rocks who love to sit on my and sometimes they get on my shoulder and one of them sometimes goes on my head, although I don't let her stay there. Anyway, one of them, Alice, was on my shoulder one time and she was picking at my hair a little and then she grabbed my ear like that. Well, of course it hurt so I reactively reached for my ear and when I did I grabbed her by the face! It didn't hurt her at all but she let out a BWAAWK and jumped down. She still likes to sit with me but hasn't bitten my ear since then.
Again, my opinion, for what its worth is that they are just being curious and exploring. I know my girls are interminably curious.
Anyway, I hope all works out well between you and Mike Tyson there. We should call you 'Holyfield'!
This is Alice...