What is nipples showing through bikini?

Nipples may show through a bikini for a variety of reasons, including the material of the bikini being too thin or sheer, the nipples protruding or being erect due to temperature or arousal, or simply due to the shape and size of the breasts. While some people may feel uncomfortable with their nipples showing through a bikini, others may not mind or even embrace it as a natural body feature. There are also options such as padded or thicker material bikinis to help avoid this issue. Ultimately, it is up to individual preference and comfort level.