I've heard the term business or busyness applied to a group of ferrets,
but has anyone ever heard of the term 'fesnyng'?  I found this link on the
collective nouns site that someone posted (can't recall who offhand) on
yesterday's FML.  The author obviously doesn't know much about ferrets,
but the article is still amusing.
 
http://www.ojohaven.com/collectives/fesnyng.html
 
Cheri, Poo, Oona, Snoopy, Alex the dog and the seven kitties
 
[Moderator's note: There's an *excellent* post in the FML archives which
seems to explain this.  It was written by Jeffrey Singman in May of 1994
and can be read at:
http://listserv.cuny.edu/Scripts/wa.exe?A2=ind9405&L=ferret-search&P=R7507
 
That URL is subject to change next month but will work for now.  BIG]
[Posted in FML issue 3622]