Gonna be lame here.
If you mean just topless, that would be the woman who flashed her bolted-on boobs in New Orleans last year.
If you mean naked, that would be the local swingers club earlier last year. Didn't get to play with anyone else but my SO, but, man, the view was nice.
Came to the stunning realization that I've pretty much never seen an IRL woman naked outside of my SO that didn't involve money, be it paying to get into a strip club, swingers club, clothing optional hot springs, or a Las Vegas show.
