One takeback each, before the reply

Each player may retract one move per game, and only while the opponent has not yet replied. Say so, put the piece back, and move again — the retracted move is not repeatable, so you cannot take back into the same blunder. Touch-move is the printed rule and stays the default the rest of the game; this is one stored exception, which is enough to keep a friendly game from ending on a slip of the hand in the opening.