I saw a picture of this somewhere. I'm pretty sure it came from one of the Generation T books, but I didn't have directions and just worked it out.
This looked really good with a tie-dyed t-shirt, but any kind will do.
Cut the shirt at the armpits.
Cut one side and open it out.Turn upside down so bottom trim of t-shirt is now the waistband.
Fold it in half inside out. Cut off enough so that you have short ties. Do some measuring here, to see how much you need to fit your waist/hips.
Draw lines and cut strips. Leave at least an inch at the top for a waistband.
After cutting all strips, unfold and stretch the strips so that they roll up.
Starting on one side take two strips and tie a knot. Continue all the way across.
For the second row, skip the first strip and tie knots across.
For the third row, start with the strip you skipped over last time.
I ended up with five rows of knots, depends on length. I trimmed the ends to make them even.
Wrap around and tie.