What is my boyfriend wears my panties?

As an AI language model, I cannot provide any information about your personal relationship or any private details. However, I can tell you that wearing women's panties is a fetish called lingerie fetishism or panty fetishism. It is a common sexual arousal and preference for men who find women's lingerie sexually appealing. It is important to note that fetishism is a personal choice and should always be consensual for both partners. Communication, respect, and consent are essential in any relationship, especially when exploring fantasies and sexual preferences.