wack

Etymology 1

Back-formation from wacky.

adj

1. (originally African-American Vernacular, slang) Annoyingly or disappointingly bad, in various senses; lousy, cringy, uncool, messed up.
   Every record they ever made was straight-up wack.
   Ya'll are so wack. 15 September 2003, Michael Chapman; Matthew Chapman, “Teen Girl Squad Issue #4”, in Homestar Runner, spoken by Strong Bad as Cheerleader (Matthew Chapman)
   The next day, Phonte gets in, and I let him hear the song, and he goes, 'This dude is wack, but what’s up with that beat though?' And I said, 'It's ours.' 2011-05-20, 9th Wonder (quoted), Jaeki Cho, “9th Wonder Tells All: The Stories Behind His Classic Records”, in Complex
   When TMZ asked Bieber whether he can listen to The Weeknd’s music, the pop superstar replied, "Hell no I can’t listen to a Weeknd song. That shit's wack." 2017-01-23, Colin Stutz, “Justin Bieber Says He Can't Listen to The Weeknd's 'Wack' Music”, in Billboard
   "No, no, no," James said Wednesday (via ESPN). "That's wack. That's wack. Why? You got to earn your spot to be in the postseason. No consolation for finishing last. That's corny. That’s corny. That's wack. To play for what? What are they playing for?" 2018-03-21, Des Bieler, “'That's wack': LeBron James doesn't like idea of NBA postseason play-in tournament”, in Washington Post
   "He's so wack for that," Jeffryes said of Prescott. "As a black man you should want to speak out against police brutality and racial injustice. You have a black father. One day you will have black children." 2018-09-19, Chauncey Alcorn, “Dak Prescott takes heat from Dallas Nine protester after Cowboys game arrests: "He's so wack"”, in Mic
   While it's not clear what the offending post was that resulted in removal, it is evident that he's not happy about the decision. "I'm done with Instagram this shit is wack,' he wrote. 2018-10-03, Joe Price, “50 Cent Quits Instagram Over Post Being Taken Down: 'I'm Done'”, in Complex
   Or, just as likely: Bobby thinks that guy is wack and sucks at Fortnite, and he doesn't accept Ryland's friend request. Next game, he'll go for the shotgun. 2021-06-10, Cecilia D'Anastasio, “How Roblox Became a Playground for Virtual Fascists”, in Wired
   […] but if there's somebody out there that's like, 'Oh, his music is wack,' what they're really saying is he's wack... But he's like, 'I don't give a fuck 'cause this isn't even really me.' 2022-07-20, Logic (quoted), Joshua Espinoza, “Logic Says 6ix9ine Is One of Many Rappers Who Put Up a Facade: 'That's Not Really Who They Are'”, in Complex

noun

1. An eccentric; an oddball; a weirdo.
2. (dated, disco-era drug slang) PCP, phencyclidine (as also whack).

Etymology 2

Clipping of wacker (“a Liverpudlian; a resident of Liverpool, England”)

noun

1. (UK, Liverpool) A friendly term of address.
   A few well chosen words such as "Let's be having you wack!", works wonders. The dockers know that they've got a Scouse to deal with. I'm not saying that a Southerner couldn't handle the situation, but the job might well take longer. 1966, The British Journal of Photography, volume 113, H. Greenwood, page 17
   Leading Seaman Hanlon, a tough young man from the Liverpool docks, greeted him with, 'Wot's up with you, wack? Lost yer bleeding maor summat?' 2011, Douglas Reeman, Torpedo Run, Random House
   One of the young men stepped forward to explain. It was obviously an enthusiasm of his. 'Hey, Wack, gerron wiv it, eh?' 2019, Richard Woodman, Voyage East, Canelo