I saw this on Pinterest (of course):
I saw this on Martha Stewart a long time ago. She even has a video! I love you Martha!
Here is a great tutorial (let's not re-invent the wheel)
For a no-sew version, line up both sides of the shirt, and cut 2 inch strips. Then, tie in knots along the bottom. Voila!
I made one for my Secret Santa. They would make great grocery bags- would fold up neatly into one!