I did that and have a fading scar to prove it, you only do it once though. The Futur can become slippy in use with just water and it has a tight mechanisims so it happens to most Futur owners, it is just a matter of time and how much damage you do when it does happen.
There should be a "I have have tried to cut my finger off with a Futur" T-Shirt that comes with it.