“The gentleman will take a chance” (eating hash)

Hash has long been called “mystery” in restaurant slang. What is it? Where does it come from?
 
An old joke has a customer ordering hash, and the waiter shouts to the kitchen, “The gentleman wants to take a chance!” The next customer also orders hash and the waiter shouts, “Another sport!”
   
The joke appears to date to June 1910, from the New York (NY) Evening Sun. The joke was soon widely reprinted.
       
       
Wikipedia: Diner lingo
Customer will take a chance: hash
     
6 June 1910, Kansas City (MO) Star, pg. 6, col. 2:
The Waiter’s Fluent Tongue.
From the New York Evening Sun.
(...)
“Hash,” says a customer. “Gentleman wants to take a chance!” shouts the waiter. “I’ll have hash, too,” says the next customer. “Another sport!” shouts the waiter.
 
Google Books
July 1910, Case and Comment, pg. 94:
Mystery of Mysteries.—What is hash?
(...)
The truth will yet be known. Daily the servitors in the least pretentious eating-houses come perilously near telling. For if you go to a very cheap restaurant and order hash, you will hear the tough waiter shout your order to the cook: “One review of reviews!” Or perhaps the dialogue is in this form: “Hash,” says a customer. “Gentleman wants to take a chance!” shouts the waiter. “I’ll have hash, too,” says the next customer. “Another sport!” shouts the waiter.
 
23 July 1910, Logansport (IN) Chronicle, pg. 8, col. 2:
I went to one of these quick lunch restaurants in Detroit with Jim Douglass and Burrill Booth and this is what I heard:
(...)
“Hash,” says a customer. “Gentleman wants to take a chance!” shouts the waiter. “I’ll have hash, too,” says the next customer. “Another sport!” shouts the waiter.
 
Google Books
August 1910, Every Where, pg. 373, col. 1:
Hash, “Guest wants to take a chance!”—Order for hash from next customer, “Another sport!”
   
31 March 1911, Mansfield (OH) News, “Hash House Terms Not in Dictionary,” pg. 5, col. 3:
Two unsophisticated people, neighbors, who have come from Crestline to Mansfield to do their trading, innocently scan the bill of fare. One of them seeing hash on the list and remembering the kind his mother used to make, tells the waiter he will take hash. “Gentleman wants to take a chance,” the waiter yells to the cook. The second gentleman does not see anything he is familiar with so he tells the waiter, he will take hash, too. The waiter sticks his head through the swinging door an says, “Another sport from Crestline.”
     
Google Boos
American Speech
By American Dialect Society, Project Muse, JSTOR (Organization)
v. 11
1936
Pg. 43:
GENTLEMEN WILL TAKE A CHANCE. Hash.
   
1 March 1936, New York (NY) Times, “Lexicon of the Soda Jerker: The Slang Employed behind the Counter Has Now Been Recorded by Phrase Detectives” by Helen Dallas, pg. X10:
Of more recent invention is “the gentleman will take a chance” for an order of hash.
   
25 July 1953, Bradford (PA) Era, pg. 1, col. 1:
Our oldtimer goes on to recount the colorful way the order would go if hash had been asked for:
 
“Sweep up the kitchen,” or “The gent wll take a chance.”
 
27 December 1953, Corpus Christi (TX) Caller-Times, “The Crow’s Nest” by Bob McCracken, pg. B2, col. 7:
“There was a classic order for hash—my favorite order in the language. When you ordered hash, the waitress paused a moment, looked you over carefully, then sang out over her shoulder:
 
“‘The gent will take a chance.’”