nipple tweak
チクニー 乳首オナニー 乳首責め 乳首イキ 玩弄乳头 乳首つねり
Pinching a person's nipples and rolling the tips between your fingers as if tuning the dial of a radio.
If the nipples are being pulled, it can be tagged nipple pull as well.
Use nipple rub if the person is "caressing" the nipple instead of pinching it.