Some friends and I sang through the Bohemian Rhapsody in the drunk tank at my hometown's police department. My dad plays hockey with a lot of the boys from the force, apparently they still talk about it. That was about four years ago.
If it includes online flings, then four. Two were online, and I had my girlfriend, and a girl I was fucking. It was all in the open though. My girlfriend didn't like it, but it's part of who I am.
Most often in the shower, but occasionally at my desk or in bed.