A nipple pump is a sex toy that applies suction to the nipple to increase blood flow and enhance sensation. Nipple pumping is mainly done before or during sex to enhance sensitivity and sensation. Some people practice nipple pumping regularly to enlarge their nipples over time.
More About Nipple Pump
Nipple pumps are made much like a penis pump, but instead of a cylinder-shaped piece they have a bulb or cone shaped piece to go over the nipples. They may be pumped manually, or include a mechanical pump.