Of course I forgot to take pictures while making it but I'll try to explain using the pictures below.
Ask your man nicely if you can cut up one of his old shirts... or just find one at a thrift store.
Cut along dotted lines
Fold vertical edges in 1/4 inch. Iron. Fold another 1/4- 1/2 inch iron. sew about 1/4 of an inch along edge to hem. Do this on both vertical edges.
Cut your 4 yards of bias tape in half to make 2 yards each. Start at the back of the neck, place your raw edges into bias tape and pin as you go down diagonal edges. Make sure you leave extra to use to tie around your back. Do the same with the opposite side. Sew 1/8 from your bias tape tape edge all the way through.
You can purchase bias tape from Joann's fabric store, Walmart, etc. Or you can make your own using the extra fabric of the back of your man's shirt. This is more time consuming but it can be done.
Here's the finish product below.