have a screw loose

Syn.
have a bat in one's attic
have a bee in one's bonnet

[one sandwich short of a picnic]
have a slate loose
nowhere near normal
SEE [не все дома]
...
Meaning: to not be right in the mind, to not be sane

Example 1: "You want me to ask that old woman for advice? She just used her sandwich as an ashtray and you don't think she has a screw loose up there?"
Example 2: He is a war hero. They were gonna make him an admiral before they found out he's got more screws loose than a Studebaker. ("Men of honor" ) — Он был героем войны. Его собирались сделать адмиралом, но потом выяснили, что у него больше винтиков не хватает, чем в Студебеккере. ("Военный ныряльщик")

син.:
[шариков не хватает]
крыша поехала
крыша потекла
[сорвать башню]
[сносить крышу]
с тараканами