"No matter how thin you slice it, it's still…

“No matter how thin you slice it, it’s still baloney” means that you still get “baloney” (nonsense), no matter how little you take of it. Variety slang writer Jack Conway popularized the slang “nonsense” meaning for the word “balogna” or “baloney” in the early 1920s. Al Smith (1873-1994), the New York governor who ran for president in 1928, frequently used the “baloney” slang term in 1928 and in the early 1930s.

“No matter how you slice it, it’s still baloney” has been cited in print since at least 1926.

Wiktionary: no matter how thin you slice it, it’s still baloney
Proverb
no matter how thin you slice it, it’s still baloney
(chiefly US) Regardless of how many clever points or fine distinctions one makes, what one is saying is still false or is still nonsense.
1933, “Topics of the Times,” New York Times, 29 Nov., p. 18:
Some of our leading scholars trace it back to a favorite American saying of that time, “No matter how thin you slice it, it is still boloney.”
2002, Dave Distel, The Sweater Letter, ISBN 0595259332, p. 267:
“Do you have the ability,” he asked another juror, “to discern between the truth and baloney?”
“I think so, definitely.”
“No matter how thin you slice it, it’s still baloney, right?”

(Historical Dictionary of American Slang)
1927 in Robinson Comics 67: That’s a lotta baloney! An’ no matter how you slice it it’s still baloney!

Baltimore (MD) Sun
9 May 1926, Baltimore (MD) Sun, “No Matter How Thin You Slice It: Gab Of Collegiate Papas And Self-Starting Flappers Is Always Bolognie Anyhow And In Sort Of Code” by Katherine Scarborough, pg. MS1:
“NO matter how thin you slice it.” Which, as every flapper knows is merely, bologna (pronounced “bolognie”) served in the grand manner.

26 September 1927, Los Angeles (CA) Times, pg A7:
Gene (Morgan—ed.) has a more musicianly band than before, several of the members remaining form the erstwhile Revelers’ organization. The Morganatic quip still serves in the introduction of numbers: “Next,” he remarks, “we shall hear, ‘No Matter How Thin You Slice it, it’s Still Baloney.’”

29 June 1928, Waterloo (IA) Evening Courier, pg. 8, col. 2:
Fred, but even tho it be sliced so thin it is still baloney.

Google News Archive
22 July 1928, Delmarva Sunday Morning Star (WIlmington, DE), pg. 12, col. 6:
Al Smith says he will pose for no boloney pictures. He believes boloney is boloney no matter how thin you slice it.

15 December 1928, Manitowoc (WI) Herald-News, “Collect Wolf Bounty Regardless of How Killed,” pg. 14, col. 3:
MADISON, Dec. 15—One could paraphrase the wheeze “no matter how you cut it, it’s still baloney,” by saying “no matter how you kill it, it’s still bounty.”

12 January 1929, Helena (MT) Independent, pg. 4, col. 7:
A very skillful “scientific” description of the infra-red rays and what they do, but it reminds me of Shakespeare’s observation—“No matter how thin you slice it, it is still baloney.”

3 December 1933, New York (NY) Times, “Hearst Hits Smith as ‘Morgan Agent.’” pg. 32:
“The bankers want you to pay them in hard money, in blood money, and they call easy money ‘baloney’ money.

“The phrase was invented by Mr. Morgan’s political agent, Mr. Al Smith.

“Mr. Smith is all right in some ways. He is wet and does a good song and dance.

“But in this instance it would seem that he is all wet and is giving the public the song and dance.

“Mr. Smith speaks the Tammany tongue, and the word ‘baloney’ is an important part of that limited vocabulary.

“He used it in his campaign for the Presidency. He said no matter how thin you cut it, it’s still baloney.”

OCLC WorldCat record
No matter how you slice it, it’s still sausage
Author: R H R H O
Edition/Format: Article : English
Publication: Journal of the Franklin Institute, v228 n2 (193908): 262-262
Database: CrossRef

Time magazine
Books: Alphabet Soup
Monday, Aug. 27, 1945
THE AMERICAN LANGUAGE: SUPPLEMENT I—H. L. Mencken—Knopf ($5).
(...)
But the bulk of heavy coinage has come from a slew of irresponsible, word-happy inventors, including such Menckenian heroes as Variety’s late Jack Conway (who coined baloney, S.A., high-hat, pushover, payoff, bellylaugh, palooka and scram) and the inventor of slanguage itself, Walter Winchell.

OCLC WorldCat record
“No matter how thin you slice it, it’s still baloney” : a collection of outrageous quotes
Author: Jean S Arbeiter
Publisher: New York : Quill, 1984.
Edition/Format: Book : English : 1st Quill ed

Google Books
Safire’s Political Dictionary
Bu William Safire
New York, NY: Oxford University Press
2008
Pg. 41:
“No matter how thin you slice it,” said Alfred E. Smith in 1936, “it’s still baloney.” It was one of the former New York governor’s favorite words.