If it won't fit on a bumper sticker, it's not very likely people will remember it.
Which is true?
Probably both. Unfortunately. The sound bite republic would argue that you "support our troops," or "just do it." You can definitely win a short conversation by saying "shock and awe," but it's a little more difficult to actually shock anyone, or make them awestruck.
Unless they give a shit about what you have to say already. If you can create a context for caring with your actions, it's possible to continue a conversation past three words. Maybe not so easy for most, but it's probably better than following Maurice Saatchi into the fool's paradise of one word equity, or any reasonable facsimile.
So, where does that leave us? We're not really just advertising anymore, are we?
photo thanks to Elliot Swan