Question: Is there a process to doing a Joker exchange

Answer: The first step in doing a Joker exchange is to announce it to the the receiving player. The tile to be exchanged is then handed to the receiving player and the Joker handed back to the player who requested the tile. This is often referred to as a “hand to hand” exchange. It is recommended that a player not place the tile on the table or touch another player’s tiles. Should a tile be discarded and a player did not make it clear they were doing a Joker exchange, that tile will be considered a discard and thus the player lose their opportunity to get the Joker.

Sources:  Mah Jongg Made Easy 2020 page 23 #14, National Mah Jongg League Bulletin Q&A 2018