First go to shop and find a shirt for your boyfriend.
Bring it home and find out he doesn't really like it.
Get all excited because you realize it's yours to play with.
Get your tailors chalk/pen/felt and mark out your top straps and cut around the arms.
Turn over and mark out your top straps, remember these are connected to the lines on the front.
mark out your back straps, I've done two here.. but you can do as many as you want.
You'll find yourself eying up all your boyfriends t-shirts!!!