I have had this shirt for a while. I have always liked it but it didn't hold up great in the wash and got a really boxy shape to it. When I was pregnant I decided to make it into a maternity shirt and just added some elastic to the sides.
First you cut off the top
Make sure you use a really coo dinosar ruler while measuring
Cut off arms and sew the top. See the link at the top for a real tutorial!
Take a weird self portrait to try to show how it turned out...