Green’s Dictionary of Slang

grease v.5

(orig. US milit.) to kill.

[US] Letter in Edelman Dear America (1985) 30 Jan. 92: This morning the helos from Vinh Long went out and greased 95 of the SOBs.
[US]Army Reporter Feb. in Maledicta VI:1+2 251: The wolf takes a shortcut to arrive there first, whereupon he greases grandma-san’s ass.
[US](con. 1966–73) M. Baker Nam (1982) 34: Called in artillery and really greased the fuckers.
[US](con. 1970s) G. Pelecanos King Suckerman (1998) 223: Greased a man down in Carolina as well.
[US]J. Stahl Plainclothes Naked (2002) 130: I’m not the one who just greased a senior citizen.
[US]C. Goffard Snitch Jacket 199: Ghetto kids who grease each other on the playgrounds.
J. Spades ‘Man Over East’ [lyrics] Gun shot it a grease pon them.