Green’s Dictionary of Slang

gash v.

[gash n.1 ]

(US) to have sexual intercourse.

[US]W. Guthrie Seeds of Man (1995) 270: Ain’ a-gonna gash ’er ’nough ta braing no blood. Jest sorta graze aroun’ on ’er some.
[US] P. Munro Sl. U.