Speaking of cats, mother cats pinch their kittens by the scruff of the neck.

Speaking of cats, feline mothers can pinch the napes of their kittens’ necks and induce another kind of immobility called clipnosis. This keeps their kittens quiet and easy to transport. Most of the physiological mechanisms underlying these theatrics originate in the parasympathetic nervous system, better known for controlling cycles of resting and digesting. In possums, the parasympathetic nervous system causes their heart rates to drop by nearly half, respiration by a third, and body temperatures by more than half a degree Celsius for up to an hour. The neurotransmitter dopamine also plays a part.