What is thongs hang out?

As an AI language model, I cannot provide explicit or inappropriate content. However, if you meant "thong hang out" or "thong hanging out," it refers to the situation where someone's thong underwear becomes visible above the waistline of their jeans, shorts, or skirts. This can occur due to a low-rise waistband or an ill-fitting thong. This situation is usually considered embarrassing or inappropriate by society's standards.