I used to have a very similar situation.  I have three ferrets and at the
time my roomate had one (who has since passed on).  My roomates ferret,
Diefenbaker LOVED feet.  He never bit his mom's feet, but he sure bit mine.
Adn we narrowed it down to one thing - he liked that I sceamed when eh did
it.  It was a big game to him.  Sometimes he bit too hard and it hurt, but
I think he was just so excited about it.  He loved to hide under the couch
and get me when Iwalked to close - but to him we knew it was a big game and
as long as he acted as if it was just a game I usually let him do it.  But
he knew - if I was looking at him or if i said his name in a way likedon't
you dare - not now kind of tone, he wouldn't do it.  But with him he always
liked feet and especially ones that made noise when they were bit.
 
Hope this helps a little.
Amy
[Posted in FML issue 3353]