“If it weren't for the coffee, I'd have no identifiable personality whatsoever.”
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David Letterman 12
American comedian and actor 1947Related quotes

“I'd never met coffee that wasn't wonderful. It was just a matter of how
wonderful it was.”
Source: The Killing Dance

Dates to 1899, American humor origin, originally featuring a woman upset by a man's cigar smoking. Cigar often removed in later versions, coffee added in 1900. Incorrectly attributed in Consuelo Vanderbilt Balsan, Glitter and Gold (1952).
See various early citations and references to refutations at “If you were my husband, I’d poison your coffee” (Nancy Astor to Churchill?) http://www.barrypopik.com/index.php/new_york_city/entry/if_you_were_my_husband_id_poison_your_coffee_nancy_astor_to_churchill, Barry Popik, The Big Apple,' February 09, 2009
Early examples include 19 November 1899, Gazette-Telegraph (CO), "Tales of the Town," p. 7, and early attributions are to American humorists Marshall P. Wilder and De Wolf Hopper.
Churchill by Himself: The Definitive Collection of Quotations, by Richard Langworth, PublicAffairs, 2008, p. 578.
The Yale Book of Quotations, edited by Fred R. Shapiro, New Haven, CT, Yale University Press, 2006, p. 155.
George Thayer, The Washington Post (April 27, 1971), p. B6.
Misattributed
Variant: Lady Nancy Astor: Winston, if you were my husband, I'd put arsenic in your morning coffee.
Winston Churchill: Madam, if you were my wife, I'd drink it.

Source: 1980's, Off the Wall: Robert Rauschenberg and the Art world of Our Time, 1980, p. 89

“You cannot thrash the person who makes you coffee. It's a rule somewhere.”
Source: Ever After
“I wouldn't be the person I am today if it weren't for his daily encouragement.”
Jessica Simpson
Adato, Allison; Ingrassia, Lisa; Baker, K C. (2006-06-12), "The Mane Man". People. 65 (23):107-108
About
“I'd probably be a 'Do you want fries with that?' person, because I have nowhere else to go!”
On what she would probably do if she weren't performing.
From the documentary Britney's Redneck Roots. Quote from The Guardian http://www.guardian.co.uk/print/0,3858,5264115-103689,00.html, unidentified issue.