Rock-paper-scissors game, usually pronounced "junk an' a po".
When playing jan-ken-pon: "Junk an' a PO! (show hand sign) I canna' SHOW! (show hand sign)" Or the long version "Junk an' a monk an' a socka socka PO! (show hand sign) Wailupe, Wailupe, bang bang JOE! (show hand sign)" No fair atomic bombs!
Before there was rock-paper-scissors, there was Jan-ken-pon, which basically means the same thing.
Players call out the name of the game till someone calls "Aiko desho!"