Nipple clamps

Nipple clamps are sex toys that usually come in a pair, often connected to the other with a chain. You can even buy weights for the nipple clamps to increase the pressure by creating more pinching and pain

Electrosex with a TENS unit

A transcutaneous electrical nerve stimulation – TENS unit uses electrode pads on the skin for sexual stimulation. You can set the intensity from low vibration or tingling to a high intensity that can cause spontaneous muscle contractions.