Green’s Dictionary of Slang

fuck it, got my orders; sometimes bowdlerized as finally I... or forget it...

1967		Current Sl. II:2 13: Figmo, Forget it, I’ve got my orders. Attitude of person in final days of old assignment.
1968		Army Times ‘Army Talk in Vietnam’ 10 Apr. n.p.: FIGMO: acronym for ‘Finally I get my orders.’ Especially in ‘figmo chart,’ a shortimer’s calendar, usually a drawing of an undraped female form, with numbered sections which are filled in, one each day, as the shorttimer keeps track of days to go.
2002		N.Y. Rev. of Books 13 June 5/2: The ‘short-timers’’ abracadabra magic word was figmo — ‘Fuck It, Got My Orders’.