The American set has eight jokers, more than any other kind of mahjong, and the rules around them have more edges than any other part of the game.
The one rule
Jokers can be used to make 3 of a kind or more, but not pairs.
A joker stands for any tile in a group of three or more of the same tile: three of a kind (players call it a pung), four (a kong), five (a quint) or six (a sextet). It never stands for a single tile and never for one tile of a pair.
Allowed: three 4 Dots made three ways, with one joker, with two, and with three. A group may be all jokers, as long as it is a group of three or more.
Allowed: four 8 Craks with one joker, and five 5 Bams, which always needs a joker because a set has only four of each tile.
Not allowed: a pair of North is two real North tiles. A North and a joker is not a pair.
You may use a joker even when you hold the real tile. Nothing forces you to play real tiles first.
Hands where a joker can never go
Because a joker cannot be a single or part of a pair, some whole lines on the card take no jokers at all.
Not allowed: North, East, West and South, one of each, are four single tiles. None of them can be a joker.
Not allowed: the year written in tiles, 2 0 2 6, is four single tiles (the White Dragon is the zero). No joker can stand in it.
The singles and pairs hands are made only of single tiles and pairs, so they take no jokers anywhere, which is part of why they pay the most.
Allowed: in a winds hand of three North, three East, two West and three South, a joker may stand in any of the threes. The two West must be real tiles.
Jokers are never passed
Jokers are not passed in the Charleston or in the courtesy pass. If you pass one by mistake, it comes back to you and you pass a real tile in its place.
A thrown joker is dead
Nobody may take a thrown joker, not for a group and not to win. It is out of the game for good, which is why nobody throws one on purpose. A joker you no longer need is still worth holding: thrown, it helps nobody and tells everyone you are close.
Taking a joker off a rack (the joker swap)
On your turn you may take a joker that sits in a face-up group on any rack, your own included, by putting the real tile it stands for in its place. Players call this a joker swap or joker exchange.
- Pick first. Take your tile from the wall, or take a thrown tile and lay your group face up, then swap. A swap before you have picked is a mistake that can make your hand dead.
- Face-up groups only. A joker still hidden on someone's rack cannot be taken.
- The real tile must be yours. It comes from your rack. You cannot take a thrown tile in order to swap it.
- Several in one turn is fine. If you hold the real tiles for two face-up jokers, take both.
- The other player cannot refuse.
Another player has three 7 Craks face up, one of them a joker, and you hold the real 7 Crak. On your turn, after you pick, the 7 Crak goes into their group and the joker comes to you.
A player whose hand is dead keeps their face-up groups on the table, and their jokers can still be taken, as long as the group was right when it was laid down.
Jokers in a concealed hand
A line marked concealed must be built without laying any group face up until you win. You may still swap a real tile for a joker on someone else's rack, because a swap puts none of your tiles face up.
Playing with them
- A joker is worth more to a hand with big groups. Holding two jokers, lean toward fives and fours and away from the singles and pairs section.
- A face-up group with a joker in it is an invitation. If you must lay a group down, use real tiles where you can and keep the joker on your rack, where nobody can take it.
- Watch other players' face-up jokers. If you hold the real tile one stands for, that joker is yours on your turn, and a joker collected late often finishes a hand.
Practise it
The school's table plays every one of these edges, including the swap from an opponent's rack, and the Coach explains any move you ask about.
Questions
Can a joker be used in a pair in mah jongg?
No. A joker can be used to make three of a kind or more, never a pair and never a single tile. A pair must be two real tiles.
Can you pick up a discarded joker?
No. A thrown joker is dead. Nobody may take it, for a group or for mah jongg.
Can you swap for a joker if your hand is concealed?
Yes. A swap puts none of your own tiles face up, so a concealed hand may take a joker from another player's face-up group on its turn.