Wordorigins.org

There ain’t no such thing as a free lunch. Despite the claims of rabid science fiction fans and devotees of economist Milton Friedman, this bit of folk wisdom has been with us since the late 1940s. And the literal term free lunch is about a century older.

The term free lunch first appears in print on 28 October 1851 in an ad in Brooklyn Daily Eagle:

ENJOY LIFE—A rational enjoyment of life is not incompatible with spending a half hour, now and then, with CHARLEY FISBECK, corner of Myrtle avenue and Duffie’d street. He has all the newspapers, serves up a FREE LUNCH every day, keeps good oysters and the most superior drinkables in the State of Long Island.