TANSTAAFL is an acronym. It stands for "There ain't no such thing as a free lunch," so it neatly encapsulates the whole theory of capitalism in one nine-letter word.

The invention of the phrase is usually accredited to visionary science-fiction writer Robert A Heinlein, in his book The Moon Is A Harsh Mistress. There is a sign over a bar saying "Free Lunch," but it turns out that this can only be had if you buy drinks at twice the usual price.

Its fictional origins have not prevented this little phrase from being absorbed into mainstream economics. For maximum effect it should be uttered in a sneering tone whilst leaning back on your heels, right thumb hooked into the waistcoat pocket of your hand tailored Saville Row suit, left hand holding a snifter the size of a football¹ containing vintage Armagnac. The more wretched the circumstances of the recipient of this pearl of wisdom, the better.

TANSTAAFL is believed be one of the most useful phrases on Earth, narrowly ahead of This (insert name of blank thing) Intentionally Left Blank.