“Acronym for "There Ain't No Such Thing As A Free Lunch." The origin of this phrase is often misattributed to Heinlein or Milton Friedman, but it actually dates back to at least the 1930s. Heinlein's contribution was to make the acronym for it.”
The Moon Is a Harsh Mistress (1966)
Original
TANSTAAFL.
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Robert A. Heinlein 557
American science fiction author 1907–1988Related quotes

as quoted by [Stephen Hawking, A Brief History of Time, Bantam Books, 1988, 0-553-34614-8, 129]

“There's no such thing as a free lunch.”
Also often misattributed to Robert A. Heinlein because both helped popularize the expression – Friedman with a book with that title. The phrase actually dates to at least the 1930s.
Misattributed

( June 16, 2005 http://web.archive.org/web/20050617/corner.nationalreview.com/05_06_12_corner-archive.asp#066356)
2000s, 2005

"Who Was Milton Friedman?", The New York Review of Books (February 15, 2007)
The New York Review of Books articles

Source: Innumeracy: Mathematical Illiteracy and its Consequences (1988), Chapter 5, “Statistics, Trade-Offs, and Society” (p. 147)