From the shop chatterwear:

Superhero costume in the wash? So now what do you do? Say something about who you are (or would like to be) with Chatterwear. (And don t forget our other designs at chatterwear.com)
Sizes: S,M,L,XL,2XL.

Visit the Artists Store

I just finished watching Hancock, which btw was a great movie.  He definately seemed like the type of superhero who would be wearing a t-shirt like this.