I have in just about every office I've ever occupied. In the late 90's I was also in charge of the "web logging" software for the company I worked for at the time. Never any real enforcement, we just tracked all web usage in case anything came up. Every now and then i'd dig through the log to find some good new porn sites to visit. That's how I discovered the p********'s secretary liked to surf lesbian porn after hours.
Soooo very hot!!!
After that I yanked it sitting in her chair over a few times so I could smell her perfume. Loved the little secret I had on her and it made her big boobed well dressed thing oh so very erotic for me.