A player plays a stroke at his ball that is lying out of bounds. What is the ruling?
A ball lying out of bounds is no longer in play and thus is a wrong ball - see Definitions of "Ball in Play" and "Wrong Ball." Accordingly, in match play, the player loses the hole. In stroke play, he incurs a two-stroke penalty and must proceed under Rule 27-1, incurring the additional one-stroke penalty prescribed in that Rule.