These guys are offering underwear with the text of the Fourth Amendment printed over your classified areas in metallic ink, so the creeps at the TSA have to at least glance at it when scanning you.
It's a great idea, but expensive ($45 for a T-shirt), and more likely to make you feel better than to actually generate any change. It's much cheaper and (maybe) more effective to write your representatives, on the off chance they might pull their heads out of the space depicted above and take some action. On the other hand, any protest is better than just quietly shuffling through like sheep.
Here's an idea: if you can't avoid being scanned, raise your hands above your head as required, but with both middle fingers fully extended. Pretty much the same effect, and absolutely free.