But sucking isn't all you can do. "You can [also] gently massage them or use a sex toy [on them] if your partner likes a little vibration," Dr. Stubbs says. Some men (or anyone else who has a penis) like when you play with their raphe line — a literal line down the middle of the scrotum where all of their tissues fused together in utero — which can be extra sensitive. "The seam of the scrotum has a nice concentration of nerve endings, so lavishing that with attention can be super pleasurable," says Lisa Finn, a sex educator at Babeland . "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."