Hot Cockles is a children's game in which one player kneels down blindfolded, or has their face buried in another player's lap so they can't see. He or she puts one hand behind their back and is then given slaps on this hand by other players. The point of the game is to guess the player who hit them. A variant is to give the slap not on the player's hand but on their bottom.
In French the game is called "La main chaude" (which means "the hot hand"). In Swedish, it is called "Spänna Kyrka". The game was already popular in the 17th century.
Boys playing the game on a sailing ship (with rope's ends, 1895)
Swedish soldiers playing "Spänna Kyrka" (Hot Cockles).