[manpower]

I pulled something like this once. My housemate and I bet a girl we could beat her in a game of beirut, with the bet being that she had to strip for all of us if she lost. Well of course she lost, so the stripping ensued. She agreed to dance for 1 song, but was having such a good time she kept it up for a half hour. It was pretty hilarious, and while she wasn't as big into face sitting as the girl in the OP, she was a surprisingly good dancer.