Well, there's been boobvertising, assvertising, your skin as ad media, pregverts and even tattooed forehead ads so I guess teenage girls' thighs are next - and we all know this is the perfect media if you are targeting leg-men.
As it happens there's a media company in Japan dedicated to advertising on the thigh area right above the knee-high stockings. The area where leg-men can not, not look. As much a horny audience as a captive one.
The ads are temporary tattoos, and even Green day has used this media space when they advertised their latest album. If you fancy being one of the women in Japan that sells your thigh-space, you have to be over 18 and connect to at least 20 people on social media like Facebook. You also have to update your social feeds with pictures of your temporary ad tattoos. It's easier than dancing around the pole!