have a screw loose

present singular third person has a screw loose · participle present having a screw loose · participle past had a screw loose · past had a screw loose

1. slangTo be insane, irrational, or eccentric.

   "You know he really has got a screw loose in his head somewheres, an' there ain't any one but what says he's the town fool, all right."

   1916, Eleanor H. Porter, chapter 22, in Just David

   3 more examples

   Richard, glorious in new livery, [...] went with his sad message, first to the church and then to the banqueting-hall in Albemarle Street. "Not any wedding?" said the head-waiter at the hotel. "I knew they was folks as would have a screw loose somewheres. [...]"

   1871 July – 1873 February, Anthony Trollope, “The Major”, in The Eustace Diamonds. A Novel, New York, N.Y.: Harper & Brothers, […], published 1872, →OCLC, page 306, column 1

   Pete Campbell (Vincent Kartheiser) would be just another irritating office brown-noser, a prep school Sammy Glick, except that he too has a screw loose and a mystical rapport with firearms.

   2010 July 16, Alessandra Stanley, “Television: Back to Work for ‘Mad Men’”, in New York Times, retrieved 16 Jun 2016

   "A successful murder has to be 'attempted' in the first place." "We both know what matters here is how you perceive the meaning." "Any immortal who considers that a loophole has a screw loose." "For all I know, your screws..." "I vow to not do anything with the intent of Elliot getting killed, okay? Leave my screws out of this."

   2016 September 23, Dan Shive, El Goonish Shive (webcomic), Comic for Friday, Sep 23, 2016