When I was 19 I shared a 3BR apartment with two roommates...one a female friend and coworker, to whom I was very attracted. On a day when I was in the apartment alone, I went into her room and rifled through her dirty laundry till I found a pair of panties with visible traces of vaginal discharge. I then laid on her bed, pressed said panties firmly over my mouth and nose, and inhaled deeply while I masturbated.
It was a magical moment... and a memory I cherish to this day.