Green’s Dictionary of Slang

an Ingram MAC 10 sub-machine gun, as v. to fire a weapon (i.e a machine gun or shotgun) prioritizing firepower over accuracy; also used fig.

1998		Atlanta Constitution (GA) 12 Oct. 46/2: The spray-and-pray approach [...] is a shotgun approach.
1999		Guardian G2 8 July 1: It’s known as a ‘spray and pray’ because it fires 1,200 bullets in a single minute. And it’s the favourite weapon of the new breed of Yardie gangsters.
2017		Dly Spectrum (Saint George, UT) 4 July n.p.: There are two ways ou can send phishing campaigns. The first is ‘spray-and-pray,’ a shotgun approach.
2017		J.R. Lawrence My Camp 325: ‘[P]ray and spray’ (poking your gun over a wall, or round a corner, without aiming and emptying a clip) .

(gay) to ejaculate in one’s fellator’s mouth.

1941		G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
1965		Guild Dict. Homosexual Terms 43: spray (one’s tonsils) (v.): To irrumate. Also: to get (or have) one’s tonsils sprayed. To fellate or irrumate.
1972		B. Rodgers Queens’ Vernacular 188: spray somebody’s tonsils to come in his mouth.