The perineum is the area of flesh between your testicles and your anus. This spot is also fairly sensitive. Beyond that, on men, just beneath this area of skin is the prostate, a sexual gland that can be pleasurably sensitive to pressure, too. While masturbating, pay some attention to this area by stroking the skin or putting light pressure on it. Your prostate enlarges when you're aroused, and you should be able to feel its firm sponginess beneath the skin. Adding motion and pressure here should be very enjoyable. While you're at it, you can also cup your testicles with your palm as you use your fingertips to massage the perineum.