this is quite an annoying thing that a hob of mine would do, but not all the time, only when he was hyped up. try running your hand, palm up, along the ground just before you pick the ferret up. as others have mentioned slow and steady is the name of the game. if you continue to get nipped then gently force the part of your hand/finger that the wee bandit has bitten, into its mouth. it wont like it and soon enough it will probably stop this habbit. good luck