This question has vexed me until I tried it myself. I have already mentioned here that the fresh pussy smell of my GF's used panties was a huge turn on as you can see

But apart from that is the nice soft cotton and the snug fit. Having worn boxers for years this was strangely arousing!!

Why do you where panties?

My older gallery of me in GF's panties and precum is here

My newer gallery with me pulling aside the panties is here. Hope you enjoy!