Colouring books for adults just got an R rating.

Colouring in books for adults just got a bit more … adult.

What started out as an exercise in mindfulness has morphed at stellar speed, and you can now colour-in illustrations of your favourite sex positions. Yes, you read that correctly: while getting mindful and creative, you can also get a little frisky.

The Sex Position Colouring in Book: Playtime for Couples, promotes ‘fun’ and ‘educational’ colouring. Website Nerve.com describes it as “a fun spin on position education. The humor makes the book perfect for making a bride blush at a bachelorette party. It’s also a handy tool in your own bedroom”.

The book, released in 2013, has become one of Amazon's top sellers this year, following the popularity of colouring in books.

It offers 101 sex positions to colour in, including 'The Springboard,' 'The Moustache Ride' and 'The Hasslehoff.' And encourages users to always colour between the lines.

It's practically the colouring in Karma Sutra.

Just look at some of the image options:

Sheesh!

It might not float your boat - but you have to admit it's a cracking gift if you want to give someone a laugh.

But for now, we think we'll just stick to colouring in our birds.

A lot more mindful.

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