On whose authority? According to whom? An intentional misspelling of "Says who?" Used to express disagreement with or defiance against something that someone has just said. A: "There's no way you can win the race!" B: "Oh yeah? Sez who?" A: "You can't take those files to the police!" B: "Oh, really? Sez who—you?"
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
See Says who?
See also: Sez
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.