nobody's fool

nobody's fool idiom
A person who cannot be duped or taken advantage of, as in You can't put anything over on Ryan—he's nobody's fool. [Early 1900s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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