Hit the hay/sack
An American expression that dates from the late 19th century and means go to bed. Mattresses in those days were often nothing more than sacking stuffed with hay or straw. Hence, hit the hay and hit the sack mean the same thing. The expressions a roll or tumble in the hay or sack, which imply sexual intercourse, come from the same source, but are first attested from the mid-20th century.