Period!

period

Used to emphasize the finality of one's statement, indicating that one has nothing further to add or elaborate. I'm not going to tell you again. There is no way I am getting on that airplane—period! With our deal, you won't pay $100, only to have hidden fees and charges inflate the bill out of nowhere. If you go with us, you pay $100, period.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

Period!

exclam. . . . and that’s final! (A way of indicating that there will be no more discussion or negotiation.) My final offer is $30. Period!
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
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