Green’s Dictionary of Slang

1. (US black, also wack-ass, whacked) second-rate, phoney, unsatisfactory; a general term of opprobrium.

1979		Funky Four + 1 ‘Rappin and Rockin the House’ 🎵 When I rap Funky Four / I can never be the wack.
1980		N. George ‘Rapping Deejays’ in Buppies, B-Boys, Baps and Bohos (1994) 45: The best definition of [the whack] is that if you don’t know what it means you probably are ‘the whack’ or maybe even ‘whacked.’.
1988		Ice-T ‘Power’ 🎵 You might like me, might think I’m wack.
1997		N. Barlay Curvy Lovebox 60: Look at the pair of you. Your garms are wacked.
1998		Source Oct. 22: If he wasn’t so busy writing wack lyrics.
2001		Eble Campus Sl. Fall 11: WHACKED – strange or weird, in a negative or positive way.
2001		N. Macdonald Graffiti Subculture xi: Dry, lame, wak: Something which is bad or of substandard quality.
2002		Teen Lingo: The Source for Youth Ministry 🌐 wacked see weak [i.e. ‘no good, a bad situation’].
2004		Guardian G2 12 Mar. 13: Them laws is wack tho.
2010		A. Steinberg Running the Books 227: That penguin shit is whack. Nobody wants to watch it.
2015		P. Beatty Sellout (2016) 9: Any wack rapper whose signature tune is ‘Me So Horny’ has no rights.
2017		Guardian G2 3 Feb. 7/3: It was a whack haircut, he made me look stupid.
2022		J. Hannaham Didn’t Nobody Give a Shit 110: [A] sign [...] that read CHECK-O-RAMA in yellow caps What’s up with that wack-ass name?

2. positive, extremely good.

1999		Guardian Guide 12–18 June 59: Those dudes are wack.
1999		Observer Mag. 26 Sept. 19: While Pokemon is ‘pretty whack’, it’s not anywhere in the same league as Mortal Kombat.
2000		Guardian Guide 18–24 Mar. 28: Which must have been wack for all the ill-shit boarders and their pavements.
2001		see sense 1.

3. see whacky adj.