The crotch of my underwear is missing!

Alright so the other day I went to put on my underwear after the shower and when I did I noticed the crotch was missing.. I thought it was strange but looked past it. The next day I got another pair and it was the same way so I started questioning things. So tonight I brought the issue to my mom and she thought it was weird too. I went and looked in my underwear pile and found 2 more just like it! I don't allow animals in my room (except my cat) and the place where I keep my underwear is in a hanging organizer. Although I do keep my dirty laundry in a pile on the floor but idk what could be the prob! Does anyone know what this could be? Has anyone else ever had this happen before?