Ninjanken / 忍者んけん is a rock/paper/scissors-style game in which you can throw one of five "jutsu" (hand symbols) against other players to try to defeat them and gain scrolls.
Each round, each player simultaneously throws a jutsu while holding a Ninjanken summary card with their other hand. When a player scores by landing rock vs. scissors, etc., they move their finger along the scroll chart on their card to show everyone else their score; additionally, they must fold down the jutsu they used, which means it's now off limits for them to use.
To reset their jutsu, they must throw the "okay" jutsu — but if someone throws the "devil horns" jutsu at the same time, then the player slides their finger toward the bottom of their card. If they get horned again, they're out of the game!