Each player can never have more than four cards in his hand, so it's illegal for a player to pick up a new card before passing one to the left.
When a player collects four of a kind, he or she must as subtly as possible take a spoon and place it in front of themselves. The moment they do this then everybody else must grab a spoon. The person without a spoon is out.
Play then continues until there are two people left. They are the co-winners.