I'm not sure when I first heard about Zentangles. I know it was back before I discovered Joanna Campbell Slan's scrapbooking mysteries, because reading those kept reminding me that I wanted to give it a try. My first attempt last year was a total failure and got the idea out of my system for a while.
Then the library got a book and our power went out for two days and there was really nothing better to do. Since then, I've tried a couple more. I'm much happier with these attempts, and I can see myself doing more of this. I've got a book about Zentangling on quilts and I'm drooling about some of the tangled objects I've seen on Pinterest, especially the shoes!
Apparently, you're not supposed to use ball point pens on the backs of lined index cards, but it's not like I worry about using the proper materials for my quilting, either.