This fun little application allows you to display a yellow or red card accompanied by a referees whistle.
Imagine a group of fans all using this app. to show the referees what the right call is! It can also be used by progressive referees, or ones who have forgotten their cards!
According to Wikipedia, besides Association football (soccer), yellow and red cards are also used in a number of other sports including: Australian Rules football, Bandy, canoe polo, equestrian, fencing, field hockey, handball, mixed martial arts, race walking, Rugby, Volleyball and water polo.
Also included are green, white, blue and black cards used in sports like canoe polo, field hockey, Bandy, Rugby, indoor soccer, badminton, and fencing.