There is one funny fact. If anyone does not know, it is in the Germans, in the people, the red card is called "Arschkarte". (In other words a card card). And all because, once before, when everyone had TVs, the judges placed red cards in the back pocket of the shorts, and yellow in the load. TV viewers, seeing where the card came from, could understand what color it was (it was difficult to disassemble the color on the screen).

PS: Wikipedia describes this fact, but doubts its authenticity