I saw one the other day that was only funny when viewed in conjunction with the one stuck on right next to it.
The first one read:
"I'm against the next war, too! Give peace a chance!"
And the second one read:
"Free Tibet!"
Uhhh, since China has a claim on Tibet, and a long-standing and legal one at that, don't you think that the act of "freeing" tibet will pretty much CAUSE that "next war" you're already against?
Some people's grip on reality is simply shocking in it's depth (or lack thereof).