Nipples aren't just there to become erect and look super hot under a tight t-shirt, oh no. They're often overlooked during sex and that should be a criminal offence because they can provide so much joy. Filled with nerve endings, nipples can be extremely responsive to touch. When we're aroused, they fill with blood and can tolerate stronger stimulation the closer to orgasm we get. Obviously, as we're all different and our bodies have totally different thresholds when it comes to sensitivity , it's always best to start slowly with nipple play and gradually increase the intensity.