What is the meaning of "knock someone flat"?

The meaning of "knock someone flat" is:

to amaze someone, to surprise someone


What is the definition of "knock someone flat"?

The definition of "knock someone flat" is:

to amaze someone, to surprise someone



"knock someone flat" means

to amaze someone, to surprise someone

Example Sentences:

Girlfriend: I have some news that will knock you flat.
Boyfriend: What?
Girlfriend: I’m pregnant.
Boyfriend: Oh.

Matthew’s parents were knocked flat when he told them he was joining the army.

The magician was knocking the audience flat with his impressive magic tricks.

Media:

Knock Out