Katsu

In a real Zendo, "Katsu" is what the master exclaims before he hits you with the stick for being inattentive.

In the game Zendo, since the positions of the pieces in the koans is important to the game, it is very bad to move them. If you disturb an existing koan such that you change the positions of the pieces (and possibly whether or not it has the Buddha nature), the Master or other players may shout "Katsu!" The stick hitting part is not recommended, as this is just a game.