If you're a football fan you'll have seen the referee issue many a yellow or red card - but what about a white one?
Football history was made on Saturday when a white card was shown for the first time during a match between Sporting Lisbon and Benfica in Portugal.
But in contrast to red and yellow cards, which are shown for rule breaking and bad behaviour, the white card has the opposite meaning.
It's shown in recognition of fair play, which means showing good behaviour and sportsmanship - but is currently only used in Portugal.
Portugal introduced the white card as part of a series of new initiatives in the country, to try and 'improve ethical value in the sport'.
The move was adopted by the Portuguese Football Federation.
The new cards contrast yellow and red cards which are used to discipline players for misconduct.
The white card made its first public appearance at the weekend as referee Catarina Campos used it during a women's cup clash between Sporting Lisbon and Benfica in Lisbon.
The card was shown after someone in the stands had fallen ill, and medical staff from both teams quickly went to help them.
It received a positive reception from the crowd at the Estadio da Luz, with many cheering and applauding the decision.
The competition where the white card was used is the Portuguese equivalent of the Women's FA Cup - which has set a new attendance record for women's football in Portugal.
More than 15,032 fans showed up beating the previous record of 14,221 set in May last year.
As the card is currently only being used in one country it remains to be seen if any others will follow Portugal's lead or how fans would react if they did so.
But it has been suggested that the card could be introduced more widely especially after extra stoppage time was added at the end of each half in the Qatar World Cup.
This allows extra time to be added on for things like time-wasting, treatment for injuries, lengthy goal celebrations, substitutions, VAR interventions and yellow or red cards.
But if it were to be considered in the UK, the International Football Association Board who make and oversee the rules in the game, would first have to add it to the agenda.