This is related to a really bad itch on a males scrotum. When the itch is so bad you must place the loose sack skin between the finger and thumb. Once you have a good grab you proceed to pinch and roll the itchy skin between your thumb and finger. This usually results in a boner, from feeling so good, with masturbation to follow.
My balls itch so bad I'm going to have to use the pinch and roll technique to stop it.
The ONLY comfortable and workable way to scratch one's scrotum. Actual scratching does not work, as the scrotal entity slides around under the fingers. To achieve results, the scrotum is pinched between the fingers and rolled back and forth.
Sweetie-darling, if you really want to scratch the boys, you must remember to use the pinch and roll technique.