Green’s Dictionary of Slang

1. (also fall off) to leave; thus n. fallout, one one who leaves.

1935		H. McCoy They Shoot Horses, Don’t They? in Four Novels (1983) 17: When a contestant falls out and has to go to the pit, the partner will have to make two laps.
1937		A.E. Duckett ‘Truckin ’round Brooklyn’ in N.Y. Age 15 May 7/1: They up and [...] fall off to the corner of Lewis avenue.
1946		Mezzrow & Wolfe Really the Blues 292: Zutty and Benny fell out, and we dashed right over to Harlem.
1953		L. Durst Jives of Dr. Hepcat (1989) 3: Don’t nobody move holler or shout it’s time for the cats to fall on out.
1960		(con. c.1930) J. Havoc Early Havoc 43: Others had entered [a marathon dance] on a bet or dare and then left. Fallouts like these were expected.
1998		P. McCabe Breakfast on Pluto 72: The night with its Clockwork Orange gangs and skinheads and hippy dealers falling in and out of Ward’s pub.

2. to enthuse, to be delighted by.

1944		Cab Calloway New Hepsters Dict. in Calloway (1976) 255: fall out: to be overcome with emotion.
1944		D. Burley Orig. Hbk of Harlem Jive 138: fall out: to be aroused emotionally.
1976		Cab Calloway Of Minnie the Moocher and Me 66: I understand kids today falling out behind the Rolling Stones.
2007		J. Stahl ‘Pure’ in Love Without 161: Instead of ‘the Lord is my shepherd,’ he busted out ‘Jesus is my pimp!’ and everybody fell out.

3. (US black) to faint; to collapse, to fall asleep; often when overcome by drug consumption or excessive drinking.

1941		W. Attaway Blood on the Forge 41: Gonna drink red pop till I falls out.
1959		A. Anderson ‘Dance of the Infidels’ in Lover Man 164: That simple motherhubber done fell out.
1964		B. Jackson Get Your Ass in the Water (1974) 146: She shot a speedball toddy and fell out at the party.
1973		M. Agar Ripping and Running 145: Cause like anybody falls out, I’m tellin you right now that I’m throwin you out the window.
1985		T.R. Houser Central Sl. 22: fell out [...] ‘Nigger stole on me, I moved a few feet, then fell out.’.
1992		R.C. Cruz Straight Outta Compton 15: I [...] marched into the bedroom and fell out.
2001		G. Pelecanos Right As Rain 57: If the shit was eighty-five, ninety per cent pure for real, you’d have junkies fallin’ out dead all over the city.
2002		Simon & Burns ‘The Target’ Wire ep. 1 [TV script] Yo’ gonna fall out slammin’ shit like that one of these days .

4. to be overcome with laughter.

1945		C. HImes If He Hollers 103: It was all I could do to keep from falling out laughing.
1959		J. Blake letter 6 Aug. in Joint (1972) 142: He didn’t fall out at my small polished witticisms.
1967		P. Thomas Down These Mean Streets (1970) 17: He didn’t say anything, and everybody fell out with a laugh kick.
1977		J. Sayles Union Dues (1978) 58: Theopolis fell out laughing.
1980		E. Folb Runnin’ Down Some Lines 236: fall out Laugh uncontrollably.
1997		Da Bomb Summer Supplement 6: Fell out (v.) Laughed hard.
2010		W.D. Myers Cruisers 10: ‘So what do you have on your head?’ I asked her. ‘Mickey Mouse ears,’ she said. ‘You like them?’ ‘Yo, I’m falling out,’ I said.

5. (US black) to be surprised.

1944		D. Burley Orig. Hbk of Harlem Jive 138: fall out: [...] to be taken by complete surpise.
1975		E. Torres Carlito’s Way 67: She fell out when she saw my white Lincoln.
1992		R. Price Clockers 66: You gonna fall out when I tell you who I’m talking about.
2013		W.D. Myers Darius & Twig 16: He calls himself Midnight because, he says, that’s when they execute people on death row. You’re supposed to fall out over that little piece of crap.

6. to relax.

1952

T. Southern ‘The Night the Bird Blew for Doctor Warner’ in Southern (1973) 55: I got big eyes to get on and just fall out someplace where the cats are blowin’.

7. (US campus) to miss a class.

2014

C. Eble (ed.) UNC-CH Campus Sl. Spring 2014 5: FALL OUT — miss class or work, usually for illegitimate reasons: ‘I fell out of class today—way too hung over from last night’.