If a player has a melded Pung and he receives a fourth similar tile from the Wall (or Dead Wall), he can add the tile to the Pung and declare a melded Kong.
Melded Kong: all four tiles are placed face up on the board.
Since a Kong consist of four tiles, and you must have four complete sets plus a pair in order to be able to go out, you receive a supplement tile from the Dead Wall.
Note: Some rules restrict player's right to declare a Kong to his own turn, i.e. the player is not allowed to declare Kong after having claimed a discarded tile, but only after having drawn a tile from the Wall. For details, see Kong options.
Declaring a Kong
Goal of the game
Regular pace of the game
Declaring a concealed Kong
Robbing a Kong
Deal ends in a Draw
Faulty declaration of Out