Has Been Flat out?

adjective. totally exhausted. When I finally got home I was flat out and had to lie down for an hour. adverb informal. with the maximum speed or effort.

Have been flat out meaning?

1 : being or going at maximum effort or speed. 2 : out-and-out, downright it was a flat-out lie. flat out.

Why do people say flat out?

You use flat out to emphasize that something is completely the case.