Nippley, use as in nippy when the weather changes to colder temperatures and women don't dress appropriately while outside and their nipples become erect in contact with the cold air. It's a way to tell your friends that there is a nipple alert.
Steve and a few of his friends were standing outside the bar when a group of young women passed shivering in the cold and having hard nipples. "It's a tad nippley out this evening isn't it?" asked Steve directing the attention of his friends to the ladies boobs as they passed.