He has a fetish for wearing women's underwear and gets off on STEALING it and wearing it. Just like the old school "panty thieves".

It's a symptom he's a likely sexual criminal. This behavior typically escalates. 

https://archive.seattletimes.com/archive/?date=19950505&slug=2119295

https://www.washingtonexaminer.com/news/crime/biden-energy-official-accused-second-theft-luggage