Before we start, just to make sure I'm not misunderstood,
Ferrets are NOT dangerous, nor rodents! They are certainly not dangerous rodents.
Ferret: Pointy vicious sausage of inquisitive and antagonistic rodent doom. When caged and left to their own devices, un-desexed male ferrets will sleep most of the time. If more than one is in a cage, they will attempt to eat each other in a friendly, inquisitive kind of way. When provided with stimuli of any kind, ferrets go into a hyper-accelerated state and investigate whatever is happening to the very utmost of their physical capacity. The funniest thing about this is that ferrets have a non-existent attention span; If two ferrets are (play)fighting, they will run and leap at each other in a thoroughly entertaining fashion (a sort of polecat-jousting), but if a ferret smells or sees something interesting mid-leap, it will immediately forget what it was doing and investigate, even if it has to drag the other ferret along. When a human tries to touch a ferret in this accelerated state, it will (play)fight the human! That is, it will chew on them - not as hard as it can, just hard enough to assess the flavour of the hand that feeds it. They also love biting people on the feet. The sight of grown men leaping and running away from these 2 foot long psychopathic carnivores is probably as funny as ferret jousting (so called because they run away from each other, turn, and build up speed towards their foe, and leap for the throat).
When investigating stimuli, but not actually attacking, ferrets make an "ack, ack ack" sound which I can only compare with really old hard drives. Ferrets are born hunters, and fantastic ratters, but must be supervised at all times if they are not in a ferret-proof enclosure; they will find or make holes in your perimeter defences. Un-desexed male ferrets, even when washed weekly, have a strong musk smell which can be detected 15 meters away by humans.
Ferrets are not really affectionate, and don't make great dog or cat style pets (ours don't anyway). They are very high-maintenance pets, especially since if they are kept in a cage, they really have to be let out for a couple of hours of supervised fun each day. Even a particularly friendly ferret will try to find out what you taste like now and again. Ferrets are utterly without fear: when we got two un-desexed male ferrets, they had our bull-terrier cross, terrier, and insane cat all on the run in no time; The canine or feline would inquisitively investigate the ferret, and in much the same spirit, the ferret would munch on the dog or cat's nose. It took little convincing for the other animals to decide to appreciate the ferrets from afar, and on many occasions, cat and dogs were sent running from a creature one quarter the weight of the cat.
A word should be said about ferret locomotion. Ferrets move aound in a way which is quite unlike other types of animal; they are sort of semi-articulated. There is a lot of ferret between the front and back legs, and the way they move makes it look like the front and back of the ferret arne't co-operating. They are never quite in-line, and move slightly diagonally. When walking, they arch their long bodies into the air, which adds to the immpression of two bipedal animals in a ferret suit. They jump by quickly arching their midsection and being carried by their momentum. which is a large component of the hilarity of ferret jousting
Ferrets are funnier than anything I have ever seen on television. The ferret in Kindergarten Cop must have been sedated, or just very, very well trained. Ours would have "tasted" every little hand that tried to touch them, and then herded the kids into a corner.
Update: A worthy authority on ferrets tells me that female ferrets behave in a totally different fashion, and are not so hyperactive nor so violent.
I feel the need to clarify my position on a couple of points in light of Akasha's writeup.
Vicious: Ferrets aren't genuinely vicious; they won't attack you or really try to hurt you. However, they are far more likely to bite you than for instance a cat or dog in my experience. These bites rarely break the skin.
Rodent doom: I realise that what I wrote was ambiguous. I know ferrets aren't rodents. They are doom to rodents. Hence they are rodent doom. Just to make it clear.
Now go read Akasha's writeup. It's much better.