I wasn't aware that the tax-exempt status extended that far either. I knew that our organization could not unilaterally support any political candidate, but on first glance, I would not think that a simple shirt could be such a threat (though now, reading this thread, I can see how the shirt might be perceived as an organizational endorsement.)
Another thing, while I understand the theoretical threat, I do wonder about the realistic possibility of the IRS pursuing such a course. I guess it is better to be safe than sorry.
I thought it was cute too.

Course, those colors together generally are.