This classic riddle asks: What two words have thousands of letters? It sounds like the answer should be an impossibly long pair of words, but the clue uses the word “letters” in a different way.
The answer is: post office.
A post office can contain thousands of physical letters waiting to be sorted, delivered, or collected. The riddle is not asking for two words containing thousands of alphabetic characters. It is referring to letters that people mail.
The trick works because “letters” has two meanings: characters used in writing and pieces of mail. Most people first think about spelling, which makes the question seem impossible.
Once you switch to the postal meaning of “letters,” the two-word answer becomes obvious.
