Panty Heist Gone Wrong

My girlfriend and I once celebrated our monthsary at their house by watching romance DVDs, after which we had very steamy sex. After we both had climaxed, I begged her to let me keep her undies as her monthsary gift but she declined. But I really wanted it as remembrance so while she was dressing up after a bath, I excused myself and went to the restroom, where I knew she hung her used underwear. After I had pocketed my treasure, I returned to her room acting as if nothing happened. Once inside I decided to join my girl, who was now lying on her bed. When she turned to hug me, I pulled off the undies and started smelling it to tease her.