Yep, it's a thing now. The top 2 best sellers on are adult coloring books.

No, not coloring books filled with pictures of men's who-who-dillies and women's who-haws, actual coloring books for adults.

These are HUGELY popular. They say adults are buying them and coloring as a way to decompress and get away from their phones and laptops. They sell for 15-20 bucks a pop and Amazon has already sold millions of books.  As a matter of fact, they're selling out!