gone tonto

To act or have acted in a manner likely to cause people to think you have lost your mind.

When she found that Rick had been dating his ex, it appeared she had gone Tonto and smashed his flat up.

by Illusor December 14, 2009

Gone full tonto

taken lunacy to a new level

You've gone full tonto there, Simon

by The teacherman March 17, 2017