1. To become extremely angry or upset. My parents are going to go mental if they find out we had a party here! Don't go mental, but I think I broke your computer.
2. To become or feel crazy. I'm going mental being stuck in this cabin all week with my parents!
3. To act in a crazy, foolish, or reckless way. Too many kids start going mental when they go to college and have total freedom for the first time in their lives.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
go ˈmental(British English, slang) become very angry: My dad’ll go mental when he sees what we’ve done!
Farlex Partner Idioms Dictionary © Farlex 2017
in. go crazy; to act stupid. Another day in that history class and I know I will go mental.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.