"Stop the bad music" is now available as a t-shirt from Graniph. They are a large chain of t-shirt stores, with dozens of locations throughout Japan and several spots in Australia, Taiwan and Hong Kong (and an online shop as well).
They put my signature in the back of the shirt just below the neck, which I thought was a nice touch:
(A side note: the agreement I signed with Graniph was very artist-friendly, so I think companies like this need to be encouraged. Too often companies want the artist to give up all their rights, with aggressively written contracts. Not so with these guys. So hooray for Graniph!)