knock one’s socks off

(verb) to amaze someone, to surprise someone

Example Sentences:

Girlfriend: I have some news that will knock your socks off.
Boyfriend: What?
Girlfriend: I’m pregnant.
Boyfriend: Oh.

Matthew knocked his dad’s socks off when he told his dad he was joining the army.

The magician was knocking the audience’s socks off with his impressive magic tricks.

From the Blogs:

Video Headlines that will Knock your Socks Off

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