When the EPD policeman would come to Danebo and set up the traffic lights/cones and we road big trikes around pretending we were car drivers, yellow also mean't stop.

http://www.oregonlaws.org/ors/811.260

§ 811.260 
Appropriate driver responses to traffic control devices

(4) Steady circular yellow signal. A driver facing a steady circular yellow signal light is thereby warned that the related right of way is being terminated and that a red or flashing red light will be shown immediately. A driver facing the light shall stop at a clearly marked stop line, but if none, shall stop before entering the marked crosswalk on the near side of the intersection, or if there is no marked crosswalk, then before entering the intersection. If a driver cannot stop in safety, the driver may drive cautiously through the intersection.