One player extends their hands forward, roughly at arm's length, with the palms down.
[6] The slapper is on offense and must act with sufficient speed, because the slappee's goal is to pull their hands away, and out of the area where the hands overlap, to avoid the slap.
However, the slappee cannot flinch too much in attempting to avoid a slap: in one variation of the game, if the slappee pulls their hands away when the slapper has not brought their hands around a designated number of times in a row (normally three), then the slappee must submit to a "free slap" by the slapper.
The offensive player knocks their knuckles against the top of the defender's fist, as a more painful variant of the game.
This version is sometimes called bloody knuckles, though not to be confused with other games of the same name.