Literally a douche bag (the plural being mensae), i.e. an object one, presumably (and hopefully) a female, would use to clean one's poonene.
"Today, Tuesday, was a scorcher. On hot days, as some may know, I tend to...well...grime up a little bit. Don't get me wrong, it's only slightly. Anyway, I barely made it through video before heading out into the hallway to go to lunch. When I got into the hall, however, there was the mensah leaning against a wall. I couldn't help but seize the opportunity and proceeded to...cleanse...myself with the mensah once I had entered the bathroom. The process complete, I threw the mensah into the trash. A few weeks later, at my annual checkup, I found out that I had contracted three STD's from the mensah. I thought that I had contracted four, but it turns out that herpes is not strictly an STD."