The pacing of the delivery of a joke has a strong impact on its comic effect; the same is also true of more physical comedy such as slapstick.
A beat is a pause taken for the purposes of comic timing, often to allow the audience time to recognize the joke and react, or to heighten the suspense before delivery of the expected punch line. Pauses can be used to discern subtext or even unconscious content — that is, what the speaker is really thinking about.
Jack Benny and Victor Borge are two comedians famed for using the extended beat, allowing the pause itself to become a source of humour beyond the original joke. George Carlin and Rowan Atkinson are two other stand-up comedians well known for superior timing.
Comic timing can also be seen in the more physical forms of comedy as well. Every slapstick comedian from Charlie Chaplin onwards has relied on the physical joke being made at just the right time. The bucket of water never falls until the audience has built up for it to just the right level.
The farce is another prime example of comic timing. Here, the humour is derived both from rapid speech and rapid movement — people running into and out of rooms at breakneck speed and managing to cause havoc in the process as done to perfection in the series Fawlty Towers.
A pregnant pause (as in the classical definition, "many possibilities") is a technique of comic timing used to accentuate a comedy element, where the comic pauses at the end of a phrase to build up suspense. It's often used at the end of a comically awkward statement or in the silence after a seemingly non-comic phrase to build up a comeback. Refined by Jack Benny, the pregnant pause has become a staple of stand-up comedy.
Examples of comedians who employ comic timing
"Her ability to detonate a joke, to momentarily harness a punch line before releasing at full force, brought her Emmy-winning success in two groundbreaking sitcoms - Norman Lear's 1970s classic "Maude" and "The Golden Girls." -- Los Angeles Times, April 27, 2009
Carlin's most famous routine is his "Seven Words You Can't Say On Television", in which much of the humour is derived from a sudden, rapid-fire delivery of the seven words (see link). The remainder of the routine is a mock-scholarly analysis of why these words are not as bad as the world would have us believe. Here, comic timing is used again as Carlin moves from the rapid list to a more reasoned — but nonetheless funny — dissection of the words.
Atkinson is another example of timing in this regard. His "No One Called Jones" routine involves his reading a class roll of students at what we can assume is an exclusive English boarding school. In one version of this routine, each name is a double entendre. In this sort of routine, it is very important to use beats, as simply racing through the list would spoil the effect of many of the jokes.
Commonly recognized as the master of comic timing, Danish-American comedian Victor Borge provides even more examples of this art. Much of his routine involved references to particular pieces of classical music, opera and composers. Having learned English as a second language, Borge was known for frequently playing around with its conventions. A prime example is his question to his audience, "Is there anyone who would like to hear the famous Polonaise in A Flat by Chopin?" After hearing the inevitable calls of "Yes, yes", Borge would respond, "Very well, is there anyone here who can play it?" Another famous line is his explanation for the third foot pedal on a grand piano — "The pedal in the middle is there to separate the other two pedals...(beat)...which could be a problem for those of you who have three feet."
Borge, therefore, builds his audience up to the joke, but only delivers the actual punchline when he is fully aware that they are silent and prepared to hear it. His famous "Inflationary Language" routine demonstrates the other side of this statement. In this routine, Borge adds one to every "number in the language", (making "wonderful" into "two-derful" and so on) and his "Phonetic Punctuation" routine, wherein he assigns a sound to every punctuation mark. These routines then consist of Borge reading a story under one of these systems. The comic timing is seen by the way that he reads alternately slowly and rapidly, in keeping with the action of the story.
In addition to the uses mentioned above, a beat can serve to allow the laughter to die down after a punch line so that an unexpected second and even funnier punch line can be delivered. One example from Margaret Cho's repertoire is the following: "I performed at the only gay bar in all of Scotland. It was called CC Bloom's. CC Bloom is the name of the character Bette Midler played in Beaches. That is the gayest thing I've ever heard in my entire life. They should just call it Fuck Me Up The Ass" (laughter) (pause) "...Bar and Grill."
In his mockumentary Borat: Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan, the character Borat is coached on the importance of comic timing. He is to state "That suit is black (pause) NOT!" However, he does it with both no pause, with too long a pause, and even the word "pause."