The Perineum (Male G-Spot)
 

This is also known as the "Male G Spot"  The perineum is the penny-sized spot between the testicles and the anus.  Think of this as an "hidden overdrive button"  that will have the potential to take his orgasm over the edge. 

The perineum is said to be the "root" of the penis and like the exterior part of the penis has an incredible amount of sensitive nerve endings.  This spot is best left to play with for the hottest of moments, when he is just about on the edge of his orgasm.  During oral sex, after he is already very much aroused place a finger or knuckle on his perineum, pressing firmly in a pumping motion and while doing this you should see instant results.