The School of Hard Knocks is an imaginary school whose program of study consists only of the practical knowledge imparted by life experience. Facetiously given as a credential when one lacks actual academic credentials, poking fun at higher education to emphasize the value of one's accumulated wisdom. In the UK, the phrase 'University of Life' may be used interchangeably.

For example:

Moe: I'm a Harvard man myself. Where do you hail from?

Joe: Well, Moe, I will have you know I have a degree from the School of Hard Knocks.

The popular notion that life experience or "training" from the "School of Hard Knocks" is equivalent to formal education is often exploited by diploma mills.

English idioms