Spit-take

Danny Thomas (of television’s Make Room for Daddy, or The Danny Thomas Show, from 1953-1964) is credited for either inventing or popularizing the “spit-take.” He would take a drink from his coffee cup, someone would say something unpleasant (“Your mother-in-law’s coming over!”), and Thomas would spray the coffee out in mock frustration and surprise.
 
The term “spit gag” was used by 1975 and “spit take” by 1980. The gag could involve any liquid, but usually involves a coffee cup. Frequently, a fellow actor is splashed by the “spit take.”
 
 
Wikipedia; Spit-take
A spit-take is a comedic technique in which someone spits a beverage out of their mouth when they react to a statement during a take.
 
Example: Two characters sit at a table. Character #1 has a cup of coffee in hand.
Character 1: Did they ever find that missing toxic sludge?
Character 2: Yes.
(Character 1 sips coffee.)
Character 2: Someone poured it into the coffee urn.
(Character 1 spits the coffee all over the table.)
 
In a spit-take, the reaction is usually one of surprise. The “spit” action is overly dramatized; performers will add lots of noise and spray liquid from their mouth in an exaggerated fashion.
 
The surprise need not be related to the substance being consumed; it is a vehicle to convey shock or surprise humorously with an exaggerated visual.
 
Example: Three characters sit at a table. Character #3, wearing a yellow sweater, has a cup of juice in hand.
Character 1: *Phone rings*
(Character 3 sips from cup.)
Character 2: Hello, I’m here to congratulate you on making in on American Idol.
(Character 3 spits the drink all over the table.)
 
Danny Thomas is sometimes credited with popularizing its use in comedy.
 
Wikipedia: Danny Thomas
Danny Thomas (January 6, 1912 – February 6, 1991) was an American nightclub comedian and television and film actor, best known for starring in the television sitcom Make Room for Daddy, or The Danny Thomas Show. He is also the founder of St. Jude Children’s Research Hospital. He is the father of Marlo Thomas, Terre Thomas and Tony Thomas.
   
Wikipedia: The Danny Thomas SHow
The Danny Thomas Show (known as Make Room for Daddy during the first three seasons) is a sitcom which ran from 1953-1957 on ABC and from 1957-1964 on CBS.
     
wiseGEEK
What is a Spit Take?
A man is sitting at a breakfast table, reading the paper and sipping a cup of coffee. As he takes a large sip, his wife tells him she’s pregnant. The man promptly spits out his mouthful of coffee in a giant spray, then sputters out an exasperated “WHAT?!”. In the world of entertainment, this would be called a spit take, a comedic technique in which a performer deliberately spits out his or her beverage in reaction to shocking news delivered by another performer. When timed perfectly, a spit take lets the audience know exactly how shocked the spitter really is.
 
In terms of physical comedy, the spit take is a very old comedic device. Although stage directions may leave out the notation for a spit take, it is a popular improvisational gimmick whenever a performer wants to exaggerate his or her reaction for comedic effect. A strong reaction to an unexpected or shocking piece of dialogue is known in the entertainment world as a take. A performer may look twice at another character, for example, in a reaction known as a double take. The spit take would be another example of a comedic take a performer could use during a scene or sketch.
 
Double-Tongued Dictionary
spit-take n. an exaggerated or surprised reaction in which someone violently expels a mouthful of liquid.
Citations:
1985 Joan E. Vadeboncoeur Syracuse Herald-Journal (New York) (July 18) “Success of two new comedies depends on Hanks” p. D8: Nor does he think the public can muster a chuckle for “Danny Thomas doing spit takes. We’re too jaded now.”
1987 Rob Lowing Sun-Herald (Sydney, Australia) (Dec. 6) “Mandy Patinkin And The Princess Bride” p. 128: At dinnertime, they had to bring in the “spit-take’ rule. Nobody was allowed to talk to someone else at the table if that person had food in his mouth because it more than likely they would choke to death laughing.
1989 Turk Pipkin Be a Clown!: The Complete Guide to Instant Clowning (Jan. 9) p. 50: Spit Take: Reaction to surprise news while drinking a glass of water was so perfected by one man that it will forever be known as the Danny Thomas Spit Take. At the dinner table, Danny’s reaction to any news he didn’t want to hear results in an immediate spray of whatever he was drinking.
1991 Jefferson Graham @ Beverly Hills, California USA Today (Feb. 1) “Thomas makes room in his schedule for ‘Nest’” p. 3D: Yet, “after all I’ve done, what I’m most remembered for is the spit- take.” That’s the point in Make Room for Daddy when [Danny] Thomas would be sipping coffee, somebody would say something surprising, and he would spit it out.
   
Google News Archive
18 July 1975, Milwaukee (WI) Journal, “Comedy Star (Jack Klugman—ed.) Gives Pointers,” pg. 9, col. 3:
What’s a spit gag, Jack?
 
“A spit gag is like, oh, like Danny Thomas. Danny is drinking a cuppa coffee, and one of the characters says, ‘Your mother-in-law’s coming here for a visit.’ And Danny goes schlurp into his coffee cup. A sure laugh, but a cheap shot.” 
 
2 January 1980, Lethbridge (Alberta, Canada) Herald, pg. 62, col. 7: 
John Wayne did ride tall in the saddle, and did define American manhood for a couple of generations, but he was never noted for his ability to deliver a spit take.
 
Google Books
Batbrains
By Barbara Daniel; Trude Stone; Tom Dudzick
New York, NY: Samuel French
1981
Pg. 55:
SLATS. See, that’s a take. There’s all kinds. (Picks up mug.) I could’ve done a Danny Thomas “spit take,” but I never go all the way on a first date. (Drinks coffee.)