Actually, I don't find vandalism of public property, particularly messing with safety signs, terribly witty.
Well, I agree and disagree. The alterations look like a cling on, which means they will most likely come right off at some point. PLUS, you still know it's a stop sign, it's like a stop sign pun. You KNOW you're supposed to stop, and scofflaws aren't any more likely to fail to stop because it says poop instead of stop, than they are to run it in the first place. I think it's amusing and harmless - in THIS instance. Here, I don't think it's vandalism. And it makes people laugh and talk about it, and raising awareness of colon cancer isn't a bad thing... Real vandalism, where damage is permanent and will cost somebody money to return to 'normal' is different than I think this particular case is.