This is a bumper sticker often seen on cars driven by people who are fed up with reading the "Mean People Suck" bumper stickers on other cars. Personally, I think anyone who puts a bumper sticker on their car with any sort of political opinion is just asking for it.
I'm sick to death of "Speak up for Decency" (even though I think that's a good idea), "Speak up for Liberty" (a retort to the "decency" one), "Hate is not a Family Value" (aimed at Rush Limbaugh listeners, whether this will be admitted or not), etc.
My favorite bumper sticker along these lines is this:
"visualize whirled peas"