There ain't no such thing as a free lunch:

My memory also had this predating Heinlein, but I googled to be sure(-ish) and found http://www.uselessknowledge.com/word/freelunch.shtml which states:
In reply to:

The term free lunch first appeared in print on 23 November 1854, in Wide West published in San Francisco. It is a reference to the practice of saloons giving free meals to attract clientele. Of course the savings is illusory as the price of the drinks subsidizes the food.

The exact phrase, there ain't no such thing as a free lunch, is also first used in the city by the bay in the 1 June 1949 edition of the San Francisco News (although this is claimed to be a reprint of a 1938 editorial so it may be even older, but the original has not been found).

But is the phrase true, in your experience? What was the closest you came to getting a free lunch? And the nastiest sting in the tail when you thought you were getting one?
Rod