acid test

Meanings

1. A test involving the reaction of an acid with another chemical.
2. A rigorous test or appraisal of the quality or worth of something.
3. In the 1960s, a party based around the use and advocacy of the psychedelic drug LSD (known in slang as acid).

Etymology

From acid + test; sense 1 (“test involving the reaction of an acid with another chemical”) and sense 2 (“rigorous test or appraisal of the quality or worth of something”) refer to the use of nitric acid to test if a metal is gold; true gold is not affected by the acid. Sense 3 (“party based around the use and advocacy of the psychedelic drug LSD”) is a pun referencing the slang term acid (“LSD”). The original “acid test” parties were thrown by the Merry Pranksters group between 1965 and 1966 and advertised by the slogan “Can you pass the acid test?”