You are mid-hand, you have a joker, and you're not sure it's legal. Here is
the whole list. The rule underneath all of it is one line long, and it's at the bottom if
you'd rather learn it once than look things up forever.
The line is simple: three or more identical tiles, a joker is fine. One or two, never — no matter what the card layout looks like.
In a pair?NOTwo tiles is under the line. There is no version of this that works.
In a single tile?NO
Two jokers in the same pung?YESIn an exposure you need one natural tile in there — the one you claimed. In your own rack, no limit.
A pung made of three jokers, concealed?YESSurprising but legal. Concealed groupings have no minimum number of natural tiles.
By tile type
For winds?YESIf the grouping is a pung or bigger. The tile type never matters — only the size of the group.
For dragons?YES
For flowers?YESSame rule. A kong of flowers can contain jokers.
For soap (white dragon) played as zero?DEPENDSWrong question, and it's the one that catches people. Jokers follow the
grouping, never the tile. Where the card prints a 0 it is usually a single — in a
year, say — and a single never takes a joker. A pung or kong of soaps does.
The layouts that trick people
Some hands on the card are printed in a way that looks like a set — a year spelled out in
tiles, the four winds in a row, a string of consecutive numbers. Legally those are singles
and pairs.
In a year written out in tiles?NOThose are four separate single tiles standing next to each other.
In the four winds written out?NO
In a 1-2-3 style run of tiles?NODifferent tiles. Never a joker.
Anywhere in a "singles and pairs" hand?NOThe entire section is joker-free by definition.
The same hand, four groupings. The green ones take a joker. The red ones do not, however tempting it looks when you are one tile short.
Claiming and discarding
Claim a discarded joker?NODead the moment it lands, for everyone, permanently.
Discard a joker safely?YESNobody can take it. Whether you should is a different question.
Claim a discard with a joker already in your hand?YESThe claim is about the discarded tile completing a group. What else is in your hand is your business.
Use a joker to complete a hand for mahjong?YESAs long as it's sitting in a grouping of three or more.
The Charleston
Pass a joker on the first pass?NO
Pass one blind?NOBlind or not, no jokers move during the Charleston.
Receive a joker in the Charleston?NONobody can send you one, so no.
The exchange
Take a joker from another player's exposure?YESOn your turn, giving the natural tile it stands for. They have to comply.
Take one from your own exposure?YES
Do several exchanges in one turn?YES
Put a joker into an exposure to take a natural tile out?NOThe trade only runs one direction.
Claim a discard so you can exchange for a joker?NOA discard can only be claimed for an exposure or to win.
Exchange while playing a concealed hand?YESYou have nothing exposed, but other people do.
Take a joker off somebody's dead hand?USUALLYThe exposure stays on the table and its jokers stay live — unless that exposure
already gives the hand away as unwinnable, nonexistent or concealed. Ask before you reach.
Modify an exposure after an exchange?NOStarting an exchange locks all of your exposures for the rest of the game.
The one line, if you'd rather learn it
Three or more identical tiles: a joker is fine. One or two: never.
Every yes and no above falls out of that. The only extra thing to remember is that the
card sometimes prints singles and pairs in a shape that looks like a set — and looking like
a set isn't being one.
The longer version, including the full exchange rules and the etiquette around asking:
the joker rules, settled.
When you have read it all: the rules workbook, 105 questions with an answer key that cites the rule behind every answer, $19.