The F zone is the most sensitive area on the body.

Below the penis, along the edge of the coronal head of the penis, and up to the penis shaft is a small piece of skin connected to the penis. If the foreskin has not been removed, you must gently pull up the foreskin to find it. This small area of ??skin is called the "frenulum" or F-zone. It is one of the most sensitive erogenous zones in men. During ejaculation, the F zone is strongly stimulated by the moist and warm depths of the vagina, resulting in contraction of the man's vaginal muscles. R zone

The R zone refers to a raised "seam" in the middle of the male vagina that divides the scrotum into two parts. The skin of the scrotum is very special and is as sensitive as the vagina of a woman's vagina. If you rub back and forth along this seam on the surface of the scrotum, men will get great pleasure. If you start from the bottom of the scrotum and go up along the scrotal seam to the penis, such stimulation can help men integrate the scrotum and penis into a response unit, allowing men to achieve a more selfless state.