grass that has been mown and dried for fodder
NAmer, informal (in negative contexts) a negligible amount
You can earn up to fifty grand, and that ain't hay
hit the hay
informal to go to bed
make hay of
to make a mess or nonsense of (something)
new evidence that makes hay of his theories
make hay while the sun shines
to utilize an opportunity fully while it lasts
roll in the hay
informal, dated to make love
[Old English hīeg]