Forty forty, also known as Forty Forty In, Mob Mob, Dub Dub In, acky 123, block, Poddy,kickstone 123, Lurky, "Pom Pom", Ralio and whip, is a children's game combining elements of the games "It" and Hide and seek. One player is "on", or "it", and they must capture the other players by 'spying' them rather than by tagging.
A player is chosen as "it" and a landmark such as a tree or lampost is chosen as the base. Players who are not "it" run and hide, while "it" counts to a certain number, usually 40 or 100. "It" looks for the other players, while the players try to get to base without being seen.
If a player gets to base without being seen, they shout "forty forty I'm free", "forty forty save myself" or "forty forty in" and are then safe, waiting at base for the remainder of the game. In order to catch someone, "it" must see the person, run back, touch the base and say "forty forty I see [name]". If the "seen" player is behind or in an object, it must be specified; e.g. "forty forty I see [name] behind that tree" while pointing at it.
Players that are caught by the "it" return to base. The last person to be caught by the end of the game is "it" for the next game. Some variants make the first person caught "it" for the next game.
There are variants to allow players to be freed. In some variants, a player reaching base can say "Release, one, two, three" or a similar chant to release one or all captured players. If the last player reaches the base without being spied, they can chant a variant of 'Forty-forty, one, two, three, all saved', and all the players are freed to play again.
In one variant, the initial It is selected by a system known as Ping Pong. All those playing stand in a circle, holding out arms so that their index fingers touch whilst a designated selector says either "Ping", (zero, once or repeatedly as he sees fit) or "Pong". Once the designated person says "Pong", everyone breaks formation hurriedly as the first person that the designated person can touch becomes the It. If the designated selector is unable to touch someone by lunging or by slight of hand to the right or the left, the designated selector is free to pursue one or more of the fleeing circle that has just broken formation. However, if someone wrongfully breaks prematurely, i.e. before "Pong" is said, then the forfeit is that he is the It. 
- Opie, Peter (1969). Children's games in street and playground: Chasing, catching, seeking, hunting, racing, duelling, exerting, daring, guessing, acting, pretending. Clarendon Press.
- "Opinion: If I were in charge of ... The playground, Bianca Richmond, 10, East Acton". Children Now. 19 June 2004. Retrieved 5 December 2009.
- The Seahorse Magazine - Cannock House School Magazine 1967
- "forty-forty". Online Dictionary of Playground Slang. Retrieved 5 December 2009.