The spoon fork and knife game?

ok so i was showed this game and it goes you have three objects (a cup a pen and a book) and a spoon a knife and a fork ...so the cup cook and pen where on there floor and so0meone left the room and the rest of us picked an object then the kid came in and then the guy showing us the game set the spoon fork and knife down in front of him and he had to guess witch object we picked based on how the utensils were set down and he got it rite ...how did he figure it out ???