V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

TANSTAAFL
       There Ain't No Such Thing As A Free Lunch (slang, Usenet)


The Jargon File (version 4.4.7, 29 Dec 2003):

TANSTAAFL
 /tan'stah?fl/

    [acronym, from Robert Heinlein's classic SF novel The Moon is a Harsh
    Mistress.] ?There Ain't No Such Thing As A Free Lunch?, often invoked when
    someone is balking at the prospect of using an unpleasantly heavyweight
    technique, or at the poor quality of some piece of software, or at the 
    signal-to-noise ratio of unmoderated Usenet newsgroups. ?What? Don't tell
    me I have to implement a database back end to get my address book program
    to work!? ?Well, TANSTAAFL you know.? This phrase owes some of its
    popularity to the high concentration of science-fiction fans and political
    libertarians in hackerdom (see Appendix B for discussion).

    Outside hacker circles the variant TINSTAAFL (?There is No Such Thing...?)
    is apparently more common, and can be traced back to 1952 in the writings
    of ethicist Alvin Hansen. TANSTAAFL may well have arisen from it by
    mutation.


The Free On-line Dictionary of Computing (30 December 2018):

TANSTAAFL
TNSTAAFL

   /tan'stah-fl/ (From Robert Heinlein's classic "The
   Moon is a Harsh Mistress") "There Ain't No Such Thing As A
   Free Lunch".

   Often invoked when someone is balking at the prospect of using
   an unpleasantly heavyweight technique, or at the poor
   quality of some piece of free software, or at the
   signal-to-noise ratio of unmoderated Usenet newsgroups.
   "What? Don't tell me I have to implement a database back end
   to get my address book program to work!"  "Well, TANSTAAFL you
   know."  This phrase owes some of its popularity to the high
   concentration of science-fiction fans and political
   libertarians in hackerdom.

   [Jargon File]

   (1995-02-28)