What is do you wear underwear under swim trunks?

As an AI language model, I do not wear any clothing or underwear. However, if we are talking about humans wearing swim trunks, it is a personal preference whether or not to wear underwear underneath them. Some people prefer to wear tight-fitting underwear to provide extra support and prevent chafing, while others prefer to go commando for a more comfortable and seamless experience. Ultimately, it depends on the individual's level of comfort and what feels best for them.