happen, v. — Green’s Dictionary of Slang

happen v.

1. (orig. US music industry) to attract publicity and be successful.

1949		A. Shaw ‘Vocab. Tin-Pan Alley’ in Music Library Association Notes Dec. 44/1: A song happens...when the preparatory work results in a successful bid for popularity.
1967		Crescendo Dec. 27/4: We could either go back to New York with a flop show, or try to stay over and make a band happen.
1971		Melody Maker 9 Oct. 18/5: The guitar solo didn’t happen.
1990		B. Greco q. in Firestone Swing, Swing, Swing (1993) 353: ‘[T]he business was dying [...] It just wasn’t happening anymore’.

2. (US) to appear, to function or work.

1962		Down Beat 8 Nov. 38: It sounded like they were all striving to create and get away from the standard things, but it didn’t really happen.
1984		(con. 1964–73) W. Terry Bloods (1985) 11: With a BCD [bad conduct discharge], nothing was happenin’.
2005		W.D. Myers Autobiog. of My Dead Brother 102: ‘I don’t go to school anymore.’ ‘How come?’ ‘‘Cause it’s not happening’ .

3. (drugs) used euph. in a variety of questions, e.g. anything happening?, i.e. do you have any drugs?; nothing happening, I have no drugs, there are no drugs around.

1960

C. Cooper Jr Scene (1996) 20: ‘Nothin’s happenin’, Bertha said irritably, ‘Ain’t nothin happenin!’.

In phrases

it’s all happening

there is much activity or success, everything is working out as desired.

1984		Partridge DSUE (8th edn) 604: from 1939; but it was more widespread and gen. late 1960–1970s.
1996		Eble Campus Sl. Sept. 4: it’s all good – expression that things are working out fine.
2002		D. Rookwood ‘Feyenoord 2 – 3 Newcastle’ Guardian 13 Nov. 🌐 It’s all happening now. Anthony Lurling almost equalises for Feyenoord, Juventus go 2-1 up with a quite brilliant goal, and a Dutchman makes it 2-0 to Man Utd.

nothing happening

(US) used as a response to the greeting what’s happening? and meaning things are normal.

1964

cited in C. Major Juba to Jive (1994).

what happen? (also wha’appen? wha’ppen?)

(W.I./UK black) a general form of greeting, ‘Hello, how are you?’.

1980		(con. 1950s) M. Thelwell Harder They Come 129: Wha’ happen, Winston?
1986		R. Hewitt White Talk Black Talk 130: Wa’appen – friendly greeting.
1999		(con. 1979–80) A. Wheatle Brixton Rock (2004) 37: Wha’ppen, Brenton?
1999		Guardian Sport 12 Feb. 16: ‘Wha’appen, Dazz?’ It’s Wattsy.
2001		(con. 1981) A. Wheatle East of Acre Lane 21: Wha’appen Walker. Where you rave last night?

what’s happening? (also happening? what happenning? what’s been happening?)

a greeting, hello and how are you? what are you/have you been doing?

1952		T. Southern ‘The Night the Bird Blew for Doctor Warner’ in Southern (1973) 55: Hey, man [...] what’s happenin’?
1956		S. Selvon Lonely Londoners 113: What happening, Big City?
1960		C. Cooper Jr Scene (1996) 45: Somebody behind him said, ‘What’s happenin, Rudy?’.
1961		T. Taylor Baron’s Court All Change (2011) 130: ‘What’s happening, Mr Miller, man?’.
1970		G. Scott-Heron Vulture (1996) 90: ‘Happenin’, Lee?’ I asked as Cooly and I approached him.
1974		V.E. Smith Jones Men 29: Yeah, man what’s happenin’?
1975		D. Goines Inner City Hoodlum 32: Hey, baby! Wa’s happenin’?
1978		Observer Mag. 14 May 54: He’s also expert at ghetto-ese. ‘Hey, young man, what’ happening?’ is his invariable greeting to males on the street.
1985		(con. 1969–70) D. Bodey F.N.G. (1988) 52: What’s happenin’, bro?
1997		C. Newland Scholar 43: What’s bin happenin’ people?
1997		(con. 1970s) G. Pelecanos King Suckerman (1998) 153: What’s happening, man?
2002		‘Touré’ Portable Promised Land (ms.) 160: We Words (My Favorite Things) [...] It’s crackin. What’s poppin? What’s hapnin? What’s cracka-lackin? Whatever’s clever.