Look at the scrotum (that’s the pouch of skin holding the testicles) and you’ll see a line or seam between the balls. This small area is packed with nerve endings, so spend some time there. "Try gently massaging the seam with your thumb as you go down on your partner, or using a broad tongue to lick along the seam and up the underside of the shaft up to the tip, hitting all of those delicious hot spots along the way," Lisa Finn, a sex educator at Babeland