There have been lots of other ideas, my favorite of which is from miss_chance: dildo protest.
To quote miss_chance:
"So, from this day forward, whenever I take the T, I intend to carry at least one, maybe two, large, silicone dildos.
"I believe that the argument that "if you aren't carrying anything illegal, you have nothing to worry about," denies our basic right to privacy, which I believe being searched while carrying "objects of a personal nature" will clearly demonstrate. Or, maybe it won't do anything. I'm white and female, so my chances of being "randomly" searched are low. Still, I have to do something, and it's the best I can come up with on short notice.
"You know, if one person, just one person does it they may think he's really sick and they won't take him. And if two people, two people do it, in harmony, they may think they're both faggots and they won't take either of them. And three people do it, three, can you imagine, three people walking in carrying a bag of dildos and walking out. They may think it's an organization. And can you, can you imagine fifty people a day, I said fifty people a day walking in carrying a bag of dildos and walking out. And friends they may thinks it's a movement.
"And that's what it is: the Big Black Dildo Anti-Invasion-of-Privacy Movement, and all you got to do to join is sing it the next time it comes around on the guitar."
I'm probably too cheap to carry an expensive silicone one with me, but... a cheap, bright pink one might do the trick for those days when I don't feel like I have the luxury of time to go to jail. I'll have to visit Grand Opening soon. And then I think I'll have to put it in a ziplock with the text of the 4th amendment printed on it.