a player's penalty stack to another player's pile must be given face down. Players are not required to stop playing whenever another player shouts Gobble. You are not allowed to put a tile on another player's penalty stack. Consider handicapping the strongest player by starting them off with a few extra tiles. Filling a double gobble (a space surrounded by 4 tiles) entitles a player to offload two tiles, either one tile each to two separate players, or both tiles to the same player.