an israeli ad agency charged with getting drivers to pay closer attention to stop signs did so by slightly shifting what drivers expect to see. instead of the hand featured in the customary sign, they featured a hand with a raised middle finger. drivers probably stopped to confirm what they saw. (and to take a photo.)
communication bottom line: you can arrest attention with the slightest shift away from the routine and expected.
hat tip: some signs can’t be ignored, osocio