Question: What happens if all players decide to do a Blind Pass during the Charleston?

Answer: Occasionally, all players may want to do a blind pass during the Charleston. In such case, a process called an IOU (I Owe You) is used, starting with the East player.  Let’s consider an example where East has one tile to pass, while the other players have two tiles to pass. East would pass one tile and say, “I owe you two more.” The player to their right can then pass one blind tile to  the player on their left, and this continues in a clockwise direction.  Once East receives their full pass from the player on their left, they fulfill their IOU by passing two tiles on their right.

Source: Mah Jongg Made Easy (2020, pg. 13)