Meat to Please You - Conner Habib - ADULTS ONLY!

This one was pre-scheduled but I think is an apt choice for National Underwear Day (I think only in the USA, though Brazil has one too on another date entirely).

I think the UK would be more inclined to follow the American date ...

http://www.imagebam.com/gallery/da23b22ffefb429356bb0e220c14fd9c/