Kong

A grouping that consists of four identical tiles. 

Joker tiles are allowed and up to four Joker tiles can be used in this grouping, depending on how the grouping is exposed. 

If the exposure occurs due to claiming a discarded tile the exposure can contain up to three (3) Joker tiles. 

If the exposure occurs due to a player declaring Mah Jongg and exposing all of their tiles, the exposure may contain up to four (4) Joker tiles.