According to Seattle City Municipal Code 11.50.560 - Forbidden devices, "No person shall erect or maintain at or near a street or alley any structure, sign, light or device that is visible from a street or alley and simulating any directional, warning, or regulatory sign or likely to be mistaken for such a sign or bearing any such words as 'danger,' 'stop,' 'slow,' 'turn,' 'impound,' or similar words, figures, or directions likely to be construed as giving warning to or regulating traffic ..."