I go up and down, And most associated with a fly I can close a gown And my teeth can bite, especially if you're a guy

Neurons of a beast unliving, Or with razors, zinc and steel. Gold bonded: either nothing or something my host comes alive but neither thinks nor feels.

The name is misleading, how could it be not, for relaxing rarely happens, while sitting on the pot.

A barber's quick move, without a flub, In the salon or the shrub. A swift, tiny cut, A sound, a soft tut, The work of a sharp little club.

I hope you like murder mystery like I do, for you will need it for this riddle : The inspector crouched at the victim to get a closer look. It was lying in a ... of it's own blood. What was the victim in?