If a player announces a card, red or black, and another following player only believes the opposite color of that card, the follower unfollows the announcer.
A player believes a color of a card if it holds a card of the same color, or announced a card of the same color or received a card of the same color from a player he is following.
If a player announces a card and another non-following player has the same color of that card, the non-follower starts following the announcer.