How To Unlock: Change into 10 different pieces of clothing.
You need to wear every single piece of clothing, save for unlockables, to get this achievement. Just about every store in Fortune City has some clothes you can dress Chuck with. Some are funny, while others border to downright disturbing... in a hilarious way though.
As all other multi-playthrough achievements, there have been reports of it not unlocking when it should. Try to contain the requirements in one playthrough, to be on the safe side.