The three act structure of drama has been described as:
 
Act One—get your hero character up a tree,
Act Two—throw stones/rocks at him, and
Act Three—get him down.
 
The playwriting/screenwriting adage has been cited in print since at least 1897 and has been credited to French writers of farce. George Abbott (1887-1995), who wrote the books for the Broadway musicals Damn Yankees and Fiorello!, often used the saying, crediting it to the American playwright Augustus Thomas (1857-1934). Thomas credited French playwrights in his 1916 book.
         
 
Google News Archive
21 November 1897, Bridgeport (CT) Herald, “At the Theatres,” pg. 9, col. 3:
The best advice ever given writers of farce is in these words: “In the first act get your principal character up a tree; in the second act, throw stones at him; in the third, get him down gracefully.” This recipe Mr. Smith has followed in writing “The Wizard of the Nile.”
 
13 November 1898, Cleveland (OH) Plain Dealer, “The Theaters,” pg. 6, col. 2:
The best advice ever given writers of farce is in these words: “In the first act get your principal up a tree; in the second throw stones at him, in the third get him down gracefully.” This receipt Mr. Smith has followed in writing these two operas.
 
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Mrs. Leffingwell’s Boots, a farcical comedy in three acts
By Augustus Thomas
New York, NY:  Samuel French
1916
Pg. 7:
In constructing such plays the French have the three act formula expressed by one of their modern writers:
 
Act one; get your man up a tree:
Act two; throw stones at him:
Act three; get him down.
 
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The Fox Plan of Photoplay Writing
By Charles Donald Fox
Chicago, IL: Fox Photoplay Institute
1922
Pg. 74:
According to the old French masters, a play should be written according to this formula:
   
“In the first act, get a man up a tree. In the second, throw stones at him. In the third, get him down again.”
 
This applies to the photoplay as well. It is as simple and comprehensive a formula as can be written.
 
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Playwrighting for Broadway
By Leo Shull
New York, NY: The Author
1945
Pg. 34:
George Abbott says: “In the first act, get your hero up a tree. In the second act, have people throw stones at him. In the third act get him down.”
   
3 October 1954, New York (NY) Times, “Mr. Abbott: One-Man Theatre: His formula for ‘avoiding boredom’ is to be a producer-director-actor-author” by Gilbert Millstein, pg. SM19:
Some years later the late Augustus Thomas of the Frohman office told Abbott that the way to do farce was to “get a man up a tree in the first act, throw rocks at him in the second and get him down in the third.”
(George Abbott—ed.)
 
Google Books
How Not to Write a Play
By Walter Kerr
New York, NY: Simon and Schuster
1955
Pg. 136:
Must I really reduce my materials to George Cohan’s “In the first act, get your man up a tree; in the second act, throw stones at him; in the third act, get him down”?
   
25 March 1956, New York (NY) Times, “That Third Act—Playwright’s Terror” by George Axelrod, pg. SM14:
GEORGE ABBOTT is supposed to have said that, essentially, a play is constructed in the following way: In the first act you get a man up a tree. In the second act you throw rocks at him. And in the third act you get him down.
       
Google Books
Vault Guide to Screenwriting Careers
By David Kukoff
New York, NY: Vault
2005
Pg. 37:
The root of such a screenplay is based on a three-act structure whose dynamic has often been summed up in the following homily: Act One, get your character up a tree. Act Two, throw rocks at him. Act Three, get him down.
 
Google Books
Playwriting for Dummies
By Angelo Parra
Hoboken, NJ: Wiley
2011
Pg. ?:
There’s an old storytelling chestnut that suggests that you “get a man (or woman) up a tree; throw stones at him; get him down.”