Adult coloring books have been a massive phenomenon over the last few years, causing grown-ups to reach for their crayons and carefully color with a vengeance, all in the name of relaxation. As Sarah Halzack reported for the Washington Post, an estimated 12 million coloring books sold in 2015, and the Independent recently reported a “surge in the number of people buying adult coloring books has threatened pencil stocks world-wide as manufacturers struggle to cope with an increased demand for quality crayons.”

This trend shows no sign of stopping, with Mills & Boon about to publish a coloring book inspired by the ‘vintage glamour’ of their covers. Now you can color-in your very own Prince Charming.

As the coloring-craze continues to grip us (and while we still have pencils left) let’s take a look at some of the more weird and wonderful books out there for the most adventurous adult-children.

• Unicorns Are Jerks: a coloring book exposing the cold, hard, sparkly truth

Those damn unicorns, they’re such a bad influence.

Published by CreateSpace

• Color Me Drunk

When just drinking isn’t enough and you need to shake things up a little. Staying within the lines gets harder with each beer…

Published by Potter Style

• Snake Eyes: A Nicholas Cage Activity Book

Now you can bring the wooden actor to life with a little color.

Published by Belly Kids

• Colour Me Good Arggghhh!!!

When you feel those homicidal urges, before you reach for the machete, why not work out that stress with a little light coloring. I’m guessing the red crayon will be used a LOT.

Published by I LOVE MEL

• Coloring for Grown Ups

A coloring book with attitude that may make you question your very adult existence, including activities such as ‘Draw the person you thought you’d grow up to be’ and the walk-of-shame maze. Boredpanda highlights many more activities contained within.

Published by Bantam

If none of these have you rushing for your pencil case, nothing will!

*other coloring books do exist.