I grab a double handful of the back of the neck at or above the front shoulder and give a verbal correction, volume dependant on the dog's personality and the immediacy of the situation. Usually the verbal is a growl, as this is a technique I save for really bad offences.
The 1st time I tried it (I was skeptical), my male hit the ground before I had finished drawing a breath. It seems that a pup instinctively submits when its mother lifts it by the scruff (to carry it). I have never used it on a grown dog, as all of my animals have been well enuff trained that it isnt necessary to give more than minor corrections.