yellow card
/ˈjɛl.əʊ ˌkɑːd/noun
University
1
a yellow-coloured card, shown to a player (especially in association football) as a caution that he or she has committed a flagrant foul; a further such foul would result in a red card.
2
one of various yellow-colored cards used to verify the healthiness, vaccination status or other medical info of travelers.
3
a form to record safety concerns and adverse reactions to medicinal drugs.
4
A card sent out by a travelling dance or theatre company to request temporary personnel from a local labor union.
5
A yellow ticket.
6
a card given to British Army personnel during The Troubles.