That ain’t hay

What is That ain’t hay?

That ain’t hay definition and meaning on Dictionary terms:
That’s a great deal, especially of money; also, that’s important. For example, He’s making ten thousand a month, and that ain’t hay. Originally used to describe a sum of money that is large, this phrase was later extended to other circumstances, as in She married a titled lord, and that ain’t hay. [Colloquial; first half of 1900s]