George M. Cohan spent his boyhood on the vaudeville stage as one of “The Four Cohans.”  In collaboration with George J. Nathan, Mr. Cohan published in McClure’s Magazine for November, 1913, an article entitled “The Mechanics of Emotion.”  Here is what he has to say about some bits of business that are sure-fire laughs:  [1]

[1] These sure-fire bits of business should be considered as being equally effective when used in any form of stage work.  Some of them, however, lend themselves most readily to the vaudeville two-act.

  Here, then, are a few of the hundred-odd things that you constantly
  laugh at on the stage, though, when you see them in cold type,
  you will probably be ashamed of doing so.

(1) Giving a man a resounding whack on the back under the guise of friendship.  The laugh in this instance may be “built up” steadily in a climacteric way by repeating the blow three times at intervals of several minutes.

  (2) A man gives a woman a whack on the back, believing in an
  absent-minded moment that the woman (to whom he is talking) is
  a man.

  (3) One character steps on the sore foot of another character,
  causing the latter to jump with pain.

  (4) The spectacle of a man laden with many large bundles.

  (5) A man or a woman starts to lean his or her elbow on a table
  or the arm of a chair, the elbow slipping off abruptly and
  suddenly precipitating him or her forward.

  (6) One character imitating the walk of another character, who
  is walking in front of him and cannot see him.

  (7) A man consuming a drink of considerable size at one quick
  gulp.

  (8) A character who, on entering an “interior” or room scene,
  stumbles over a rug.  If the character in point be of the
  “dignified” sort, the power of this laugh provoker is doubled.

  (9) Intoxication in almost any form. [1]

[1] Intoxication, however, must never be revolting.  To be welcomed, it must always be funny; in rare instances, it may be pathetic.

(10) Two men in heated conversation.  One starts to leave.  Suddenly, as if fearing the other will kick him while his back is turned, this man bends his body inward (as if he actually had been kicked) and sidles off.

(11) A man who, in trying to light his cigar or cigarette, strikes match after match in an attempt to keep one lighted.  If the man throws each useless match vigorously to the floor with a muttered note of vexation the laughter will increase.

  (12) The use of a swear-word. [2]

[2] The use of swear-words is prohibited in most first-class vaudeville theatres.  On the walls of every B. F. Keith Theatre is posted this notice:  “The use of ‘Damn’ and ‘Hell’ is forbidden on the stage of this theatre.  If a performer cannot do without using them, he need not open here.”