A "22 drop-out" occurs when an offensive player causes a ball to enter a try zone (generally by way of a kick or a charge-down) which is then grounded by a defensive player. The defense then restarts play with a drop kick from within their own 22 metre line. When the ball is taken into and then grounded by a defensive player (generally the result of a well-weighted grubber that stops just short of the try line) then the outcome is a 5 metre scrum with the put-in to the attacking side.

oops *Drop Out - the way play is re-started, using a drop-kick, after the defending side has touched the ball down behind its own try-line or when the ball has gone out over the dead-ball line (I have never heard that term used but I do know the rule very well)