“Diner: How long will my spaghetti be? Waiter: I don’t know. We never measure it.”

A joke about ordering spaghetti in a restaurant is:
 
Diner: Waiter, how long will my spaghetti be?
Waiter: I don’t know, sir. We never measure it.
 
The joke was printed in American newspapers in 1975.  British prop comedian Tommy Cooper (1921-1984) is frequently credited with the joke, but it’s uncertain when—and if—he said it.
 
“Diner: Waiter, will my pizza be long? Waiter: No, sir, it will be round” and “Diner: Waiter, I’m in a hurry! Will the pancakes be long? Waiter: No, they’ll be round” are similar jokes. “How long will the next bus be?”/“Same length as this one” is a related joke.
 
     
10 August 1975, The Courier-Journal (Louisville, KY), “Funnybone,” iImes Magazine, pg. 20, col. 3:
Diner: “Waiter, how long will my spaghetti be?”
Waiter: “I don’t know, sir. We never measure it.”
Todd Murphy
New Albany, Ind.
   
28 December 1975, The Sun (Baltimore, MD), Magazine, “Sunday Punch,” pg. 14, col. 2:
Diner: “Waiter, how long will my spaghetti be?”
Waiter: “I don’t know, sir. We never measure it.”
 
Google Books
Aspects of Verbal Humour in English
By Richard Alexander
Tübingen: Narr
1997
Pg. 42:
After waiting for half an hour in a Soho restaurant the customer called over to the waiter: “How long will my spaghetti be?” he asked. “How should I know”, replied the waiter. “I never measure it.”
 
12 September 2001, Sault Star (Sault Ste.-Marie, ON), Fred Loader column, pg. B3:
“WAITER! WAITER! How long will my spaghetti be?” “I don’t really know, sir. You see, it’s not part of my duties to measure it.”
 
Twitter
LadyLeveret © ™‏
@LadyLeveret
I said “How long will my spaghetti be?” The waiter said, “I don’t know ...we never measure it!”
6:22 AM - 22 Dec 2012
 
Twitter
Dennis Martin‏
@MdsDennis
“I asked the waiter, ‘how long will my spaghetti be?’  He said, ‘I don’t know, we never measure it’” - Tommy Cooper
8:20 AM - 2 Jan 2013
 
Twitter
Wyn Lewis Jones‏
@Wynlewisjones
I said: “How long will my spaghetti be?” The waiter said: “I don’t know. We never measure it.” ...Tommy Cooper
6:00 AM - 21 Apr 2014
 
YouTube
Funnybot Tommy Cooper 5 jokes from the master of comedy
Funnybot
Published on Jan 8, 2017
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#3. I said: “How long will my spaghetti be?” The waiter said: “I don’t know. We never measure it.”