There have been "Adult" coloring books (often with a BDSM theme) being released for a few years now. Quite expensive, but I've had fun coloring the pages with o

There have been "Adult" coloring books (often with a BDSM theme) being released for a few years now. Quite expensive, but I've had fun coloring the pages with other people at events. You likely won't see sexually-explicit coloring books becoming popular on bestseller lists, due to the overall puritanical nature of the UK and the US. I wouldn't be surprised if some more liberal countries such as Denmark or Belgium's bestseller list reflected this.