Dutch uncle

Dutch uncle is a term for a person who sternly lectures, comments or criticizes with unsparing severity and blunt frankness, to educate, encourage or admonish someone, often with benevolent intent, as though an elder relative or "uncle."

Originating in the early 1800s, this expression, often put as talk to one like a Dutch uncle, presumably alludes to the sternness and sobriety attributed to the Dutch. Some, though, have speculated that it may allude to qualities attributed to the Deutsch (Germans).

Example: "When I was late for class, the teacher talked to me like a Dutch uncle."

See also: List of common phrases based on stereotypes