I was working overtime one weekend and I shared and office with two guys who weren't working that weekend to I was alone. I found myself needing extra stationery and with the stock cupboard being locked I decided to raid the guys desks.
I was thrilled when I found porn magazines in there instead and spent a good half hour rubbing my clit to orgasm over pictures of sexy naked ladies. When the guys came back in on Monday I desperately wanted to thank him and tell him what I'd done ;)