This is exactly as it sounds. A paperback coloring book with adult themes and subject matter, with coloring pages such as "Hipster or Homeless" or "Adulthood Alphabet".
It's not just a coloring book, it's an entire activity book.
I found out not too long ago that adult coloring books have been a rapidly growing industry.
Most of you already knew that, but I guess I am late to the party. The various pages contain different ideas to shake things up a bit. For example, my personal favorite is this hipster or homeless page.
Hipster or Homeless Page
This is my favorite page of the Adult Coloring book by Ryan Hunter and Taige Jensen. By the looks of the Amazon sales rank, it appears as though they are moving a lot of units, and I say good for them.
Don't Get Hurt Health Insurance Maze
My second favorite coloring page (it's touch to beat "Hipster or Homeless"), is this one, although it's mostly Americans who can relate to this one.
Navigate the maze and try not to get hurt, as you don't have the adequate life insurance.
You really need to check out some of the other pages in this funny adult coloring book here.