Meaning of the word "not know what hit you" in English

What does "not know what hit you" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

not know what hit you

US /nɑt noʊ wʌt hɪt ju/
UK /nɑt noʊ wʌt hɪt ju/
"not know what hit you" picture

Idiom

1.

to be completely surprised or overwhelmed by something, often something negative or sudden

Example:
When the market crashed, many investors didn't know what hit them.
The boxer landed a punch so fast, his opponent didn't know what hit him.
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