Avoiding the Double Kiss.. or not!
The zone is an area within a bank shot that has heightened sensitivity, the stimulation of which may result in the production of a double kiss. When the cue ball makes contact twice with the object ball it is called a double kiss. The second “kiss” (contact) is not normally intentional.
The word kiss came from Old English cyssan (“to kiss”), in turn from coss (“a kiss”). In the cue sports a kiss is an instance of contact between balls, usually used in the context of describing an object ball contacting another object ball (e.g. "the 2 ball kissed off the 12 ball"), or in snooker the cue ball making contact with some object ball after the initial contact with a ball on. If the player's intention was to cause two object balls to kiss (e.g. to pocket a shot ball by ricocheting it off a stationary one), it is often called a kiss shot. However, when banking there is a zone (area) where the cue ball and object ball produce a second unintentional collision. Once at the initial contact point and then again on the rebound. This second kiss will cause the object ball to dramatically miss the intended pocket.
You can locate this zone by seeing two parallel lines, one on each side of the cue ball. Then connecting each line to the reflected intended pocket, as shown in each of the following movies. If any part of the intended object ball is touching either line it is in the zone and there is a chance for a double kiss.
By tweaking the erogenous relationship of the A.S.S. you can avoid the double kiss.