Vehicle Code § 21465
ARTICLE 3. Offenses Relating to Traffic Devices
No person shall place, maintain, or display upon, or in view of, any highway any unofficial sign, signal, device, or marking, or any sign, signal, device, or marking which purports to be or is an imitation of, or resembles, an official traffic control device or which attempts to direct the movement of traffic or which hides from view any official traffic control device.