what are phrases that mean someone has gone crazy:

My first example:
See flew way over the cucoos nest

He's off his rocker.

She's nuts.

He's suffering from a psychological disorder.

Has she lost her mind?

She makes Norman Bates cry for his mother. (this is from the movie psycho)
He needs a checkup from the neck up.
Did your sister lose her marbles?
I was as nutty as a fruitcake.
My teacher is not the sharpest pencil in the box.
Frankly, mom is out to lunch.
Does she have screws loose?
He is round the bend, usually.
On his best days he is totally confused.
When his head was assembled, they forgot the final screw.
As mad as a March hare.

Phrases that mean someone has gone crazy often use metaphorical language to convey the idea. Here's another example:

1. "He's lost his marbles": This phrase suggests that someone has lost their mental faculties, comparing their sanity to a collection of small glass balls, or marbles.

To come up with more examples, you can consider phrases that involve the idea of irrational behavior, instability, or a break from reality. Here are a few:

2. "Off their rocker": This phrase suggests that someone has become mentally unstable, as if they have fallen or been thrown off a rocking chair.

3. "Bats in the belfry": This phrase implies that someone is behaving in a crazy or eccentric way, comparing their mind to a bell tower where bats might reside.

4. "One card short of a full deck": This phrase suggests that someone is mentally imbalanced or lacking intelligence, comparing their mental state to a deck of playing cards missing one card.

5. "Out to lunch": This phrase implies that someone is mentally absent or disconnected from reality, as if they have gone out for lunch and never returned.

Remember, these phrases rely on idiomatic expressions and are not meant to be taken literally. They are used in informal contexts to describe someone's mental state in a figurative manner.