i saw half an episode of "would i lie to you?" the other day and i'm still trying to figure out how the show works?? you tell an outrageous story about yourself and the other team have to figure out whether it's true or a lie

but it looks like the person telling the story is given a card to look at first?? what's on the card?? does it just say "lie" or "tell the truth", or are there actual stories on there you can pick from, and if there are wouldn't they all necessarily be lies???