I've never been one to buy clothes in my size - I've always been a fan of the oversized look.  Often I'll buy a shirt in XXL and wear it as a dress.  I think my biggest success in this endeavor is the dress I wore on New Year's Eve - I found a beautiful black sequined Reiss dress on Brick Lane last year in London, and though it was a size 14 (I would say I'm normally a 4) I bought it anyways.  I ended up with this 20's flapper girl vibe, which only goes to show, size doesn't matter.