Caught my 15 year old son wearing my thong

I’m a mom of 3 boys. One is 15, and the other 2 are 12 (they are twins). Saturday my oldest son had his door shut but not all the way. He had his music loud so I went to ask him to turn it down. When I went to open it I could see him through the small opening since it wasn’t fully shut and he was wearing one of my pink thongs!! I immediately walked away so shocked, and completely lost on how to handle the situation or if I should even do anything hoping it was a one time/phase thing. So today while he was out with his dad I snooped through his room which I normally never would do, but I considered the situation making it ok for me to invade his privacy. Under his bed in a shoe box I ended up finding 3 pairs of my thongs which I’m assuming he is wearing since I saw him wearing the pink one. I want to try to handle this without my husband knowing because he would flip out. Advice please!! Thanks.. concerned mom of a teen boy.