This is an extremely effective mini illusion, easy to carry and perform, and guaranteed to make an impact on any audience.
In effect the performer places a frame with a wooden box over his assistant’s head. The head is then clamped into the box and the box is turned slowly, twisting the head with it. It is turned right around and then twisted back again in the opposite direction to unscrew the head. Finally everything is removed and displayed freely, and the assistant is completely unharmed.