I used to wear a t-shirt with the TIA "Total Information Awareness" all-seeing eye logo on the front, and the slogan "Be A Good American. Don't Ask Questions." on the back, when I traveled. It was sometimes good for a few laughs with foreign border agents; but on the US side, never even so much as a smile. OTOH, I never got singled out for "extra screening" because of it (as far as I can tell); but that seems to be more common these days.

TBH, if I thought such a weak form of protest would really draw a response from TSA agents, I am pretty sure I would wear it. Maybe that's part of the reason I avoid flying these days.