Squirt is a term coined, I believe by Robert Byrne, to describe a cue ball hit, whereby the cue ball accidentally diverges from an intended path. The divergence is caused by too much left or right spin, a cue stick shaft that bends too much upon impact, or both. When it happens, it may appear like a curve, but squirt and curve shots are quite different.
A curve shot occurs when top or bottom english is combined with right or left english, causing the cue ball to spin on an oblique axis: that is, an axis other than completely vertical, or completely horizontal. The ball's path actually curves off the straight line. A curve shot is often used by advanced players to curve around interfering balls.
A squirt shot is the result of a poor hit. (See diagram above.) The cue ball diverges from the original straight path, but it does not (necessarily) curve. The cue ball is simply driven off to another straight path, usually unintentionally. Like the curve shot, squirt can be used by extremely advanced players. Most of the time, players who compensate for squirt do not know they are doing so, or if they are aware, may not know why.
I used squirt for years, and didn't know it. Compensating for the anomaly was instinctive and automatic. I was watching a Robert Byrne tape one evening when the shot was described. I recognized it immediately as something I used on occasion. The illustration above is an example of one of the occasions I used squirt.
I could, it appeared, cut the object ball off the rail into the pocket, although the angle of the hit was much greater than 90 degrees (see diagram above.) I aimed almost directly at the object ball, with right english that was so severe, that the ball squirted left, changing the path. The cue ball hit the rail a fraction of an inch behind the object ball and spun off the rail sinking the object ball on the rebound. I use the past tense, because I have changed my shooting techniques. I stopped using unorthodox methods, in an effort to become more consistent.
Circus shots are great for showing off when there is no pressure. But under the pressure of a tournament, they often fail. Furthermore, there is always a great risk of scratching. I see no reason to learn squirt, since it is a low percentage shot at best. I developed it, many years ago, when I was trying to compensate for extreme spin that I shouldn't have been using to begin with. Like many other "show offs" who never competed against serious shooters, I developed bad habits, and compensated my way out of them. I describe it here, not so that you will learn it, but so that you will recognize it when you accidentally squirt...in pool that is