狡い (ずるい /ZURUI) adj. Unfair.
Or, more precisely, “No fair!” Heard most often when playing a game. “Teacher, he got three cards! No fair!” Sometimes my little Justice Kids, who have to make sure everything is perfectly fair, overuse this word. I make it a goal to organize activities so that no kid can cry, “Zurui!” at any point. It’s totally fair, kid. Them’s the rules of the game!