Sleeveless Stripe Front with Bow. Use old white t-shirt to make the "sleeve" part on the girl scout shirt. That will allow a wider sleeve area and a bow. Just match it with an earlier post on my sewing board.
DIY Macrame Back Tee Shirt Tutorial from Trash to Couture here. There is a link to a really good video on how to macrame the back that Trash to Couture made. From personal experience I find it better to err on the side of too long of strings/rope/tee mate