Noun
school of hard knocks (plural schools of hard knocks)
(idiomatic, chiefly US) The source of an education consisting of real-world experiences, especially adverse experiences.
His most renowned projects are his School of Hard Knocks. Source: Internet
This is the first major concert presented by School of Hard Knocks on the Sunshine Coast and also the first time Dr Jonathon Welch has performed on the Sunshine Coast. Source: Internet