(as) silly as a wheel Australia simile
If you say that someone or something is as silly as a wheel, you mean that they are very stupid or silly.
He was as silly as a wheel when he believed in the woman who took advantage of his gullibility to scam him twice.
Her idea of using water to extinguish a blazing flame that derived from the gas leak is as silly as a wheel.
Extremely stupid
A very offensive term used to describe an upper-class British man who is stupid or inexperienced
Stupid or crazy
To be extremely stupid; not to be alert
The origin of this idiom is not clear.
Used to describe a person being more careful after an accident or a bad experience in the past to avoid it happening again.
I drive more carefully after an accident when I was little because a burnt child dreads the fire.