THE news that Discovery Bay Golf Club will be the first in Hongkong to introduce night-time golf with the aid of extensive flood-lighting reminds us of a conversation between two golfing buddies about to tee-off in just such a night-time game in another part of the world. Golfer 1: ''Bit unusual isn't it, that ball you are tee-ing off with?'' Golfer 2: ''Oh yes, it's ideal for night-time play because this ball is impossible to lose.'' Golfer 1: ''How come?'' Golfer 2: ''Well, if it goes in the rough it starts flashing and on the fairway it emits a beep so you can locate it easily. What's more, no sooner it hits water, a pair of tiny fins automatically protrude from the ball and it swims to the edge.'' Golfer 1: ''How amazing - where did you get this ball from?'' Golfer 2: ''Oh, I found it.''