How to deactivate a Cat

This doesn't work on all cats.

and is seen by the cat as punishment, so don't do it without a reason unless you're training your cat to be a dick.

It's a left over reflex from kittenhood, their mother used to grab them by the neck to move them or shut them up. so they go still to prevent their mother from dropping them.

Still it can be useful with cats that do not allow their nails to be cut or ears checked.