TNSTAAFL 

/TAN-staf-ful/ intj,n,v: "There's no such thing as a free lunch." Coined from Robert Heinlein's "Stranger in a Strange Land." Ended up on the Martian flag.

Also appears in several other Heinlein novels, including "The Moon is a Harsh Mistress," where all restaurants served the meal free, but charged heftily for beverages, etc.

More widely used around the time the book was first published, but can still be found circulating in dark basement apartments and gaming stores everywhere.

"I told you she'd be wanting payback for those smokes, man. TNSTAAFL."

"I answered that ad for a free RAZR and now all I get in my inbox is spam. TNSTAAFL strikes again."

"That new pizza joint totally TNSTAAFLed us."

TNSTAAFL by somnambulist June 11, 2006

tanstafl 

There Ain't No Such Thing as A Free Lunch.

Very old slang, dating back to before ain't became a legitimate English contraction.

I means that a prospect is too good to be true(TGTBT), in that you are being offered something for nothing.

Nate: Your eMail says Bill Gates will give you $250 for each person you send this to that sends it to someone else.

Uncle Dick: TANSTAFL.

tanstafl by Ronin Catholic January 3, 2008

TINSTAFL 

An acronym for "There is no such thing as a free lunch."

"When in doubt, just remember TINSTAFL!"

TINSTAFL by neops August 13, 2005