The Mush (Article ID 156)
A “mush” is a house rule not sanctioned by the league. It is a non-compulsory exchange of tiles after the Charleston optional across pass. Players who choose to participate place tiles to be exchanged in front of their rack, upside down. Participating players take back from the other players as many tiles as they contribute, in turn.
The standard number of tiles that can be exchanged in the mush is three, but some groups mush up to five tiles. Another variation of this table rule is doing a mush after the first Charleston, then continuing with the second Charleston if all players are in agreement.