Green’s Dictionary of Slang

weak adj.

1. lacking in funds, poor.

[US]E. De Roo Young Wolves 53: ‘Too expensive,’ Roy told him flatly. ‘I’m weak.’ ‘They’re on me.’ ‘No. I’d have to owe you.’ ‘So owe me, if that’s the way you want it, but I’m strong tonight. Got plenty of vitamins.’ He waved a couple of bills.

2. poor, disappointing, ineffectual.

[US]H. Salisbury Shook-Up Generation (1961) 172: WEAK Bad, poor, disappointing, unconvincing.
[US]D. Claerbaut Black Jargon in White America 86: weak adj. 1. inadequate; inferior. 2. inappropriate; not timely.
[US]P. Munro Sl. U. 202: weak no good, not up to standard, lame.
[US](con. 1946) G. Pelecanos Big Blowdown (1999) 91: They sound like one weak tit.
[US]Simon & Burns Corner (1998) 248: I kicked your weak ass up and down the street.
[US]UGK ‘Swisha And Dosha’ [lyrics] Weak niggaz wanna plead their case (case), just to raise up out my face (face).
[US]G. Pelecanos (con. 1972) What It Was 83: He wasn’t excited about it. Music for females and pretty boys. It was weak.

3. stupid.

[Aus]Lette & Carey Puberty Blues 51: No bull? What a weak act.
[Aus]R. Beckett Dinkum Aussie Dict. 56: Weak: Short for ‘piss weak’ or ‘weak as cold piss on a plate’. The person being referred to is a doddering idiot.
[Aus]R.G. Barrett White Shoes 107: I guess that was a bit of a weak act [i.e. informing on a friend's adulterous affair].
[US]T. Parker South Park: Bigger, Longer and Uncut [film script] dr doctor: Great! Son, I have some bad news. We...accidentally replaced your heart with a baked potato. You have about three seconds to live. [...] kenny: What? [exploding] cartman: Ah! Fuckin’ weak, dude!
[US]Mad mag. Feb. 28: This is so weak. Weak? This is the NFL!

4. (US campus) frustrated.

[US]Eble Campus Sl. Mar. 10: weak – frustrated.

In compounds

weak-ass (adj.) [-ass sfx]

a derog. term for second-rate, unimpressive, powerless.

[US]N. Algren ‘Watch Out for Daddy’ in Entrapment (2009) 147: Some kind of old country barn with just one weakass bulb burning high up.
[US](con. 1986) G. Pelecanos Sweet Forever 43: Man had a conk. Clay couldn’t believe it, and a weak-ass moustache.
[US]Simon & Burns ‘Hot Shots’ Wire ser. 2 ep. 3 [TV script] Sounds like some weak-ass shit to me.
[US]W. Ellis Crooked Little Vein 102: You East Coast types [...] You’re like little weakass colonies on the edge of Real America.
weak shit (n.)

1. (drugs) second-rate, relatively ineffective drugs [shit n. (5c)].

[US]G. Scott-Heron Vulture (1996) 80: He [...] started runnin’ off at the mouth about blowin’ yawl’s mind wit’ weak shit.

2. second-rate, weak, inadequate words or actions [shit n. (3e)].

[US]D. Goines Street Players 12: Aw, man, why you come up with that weak shit?

SE in slang uses

In derivatives

weakie (n.) (also weaky) [sense 2 + sfx -ie]

(Aus.) an unreliable, untrustworthy person.

[Aus]D. Niland Shiralee 53: Don’t lump me in with the weakies.
[Aus]W. Dick Bunch of Ratbags 34: He was not going to be a weakie.
[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xliii 11/2: weaky: A person who gives in easily, usually a young female who does not fight too vigorously for her honour.

In compounds

weakheart (n.)

(UK/W.I.) a derog. term for a police officer.

[UK]D. Powis Signs of Crime 207: Weakheart West Indian slang for police. Meant to be offensive.
[UK]J. Morton Lowspeak.
weak-jointed (adj.)

(US) euph. for drunk.

[US]Kalida Venture (OH) 11 Apr. 2/4: Drunk [...] weak-jointed.
[US]Burlington Sentinel in Hall (1856) 461: We give a list of a few of the various words and phrases which have been in use, at one time or another, to signify some stage of inebriation: [...] weak-jointed.

In phrases

weak as gin’s piss (adj.) (also weak as a pygmy maiden’s piss, breath, ...nun’s piss, ...puppy’s piss, ....weasel’s piss) [gin n.1 (1) + piss n. (1)]

(orig. Aus.) extremely weak.

[Aus]Baker Aus. Lang. 88: Of additional similes peculiarly our own, the following are among the best: [...] tea as weak as gin’s p—s, very weak tea (maids-water is used similarly).
[US](con. 1940s) S. Longstreet Pedlocks (1971) 380: Peter sat with Mike Kozloff, drinking a warm, bitter ale, ‘weak as cat breath.’.
[Aus]F.J. Hardy Outcasts of Foolgarah (1975) 15: Those showers have got a stream as weak as a pygmy maiden’s piss.
[UK]A. Bleasdale No More Sitting on the Old School Bench (1979) 17: The state of you, arty-farty, weak as weasel’s piss.
[NZ]McGill Dict. of Kiwi Sl. 121/1: weak as nun’s piss very weak, often a reference to beer.
[Aus]G. Seal Lingo 133: The problems associated with over-proof and downright dangerous concoctions are also numerous in colloquial speech: [...] blow-me-skull-off; the offensive gin’s piss.
[US](con. 1975–6) E. Little Steel Toes 16: I’m weaker than puppy’s piss, no stamina and no power.
[NZ]McGill Reed Dict. of N.Z. Sl. 227: weak as cat’s/gnat’s/nun’s/weasel’s piss Feeble and unthreatening.
weak as piss (adj.) [piss n. (1)]

extremely weak (cf. piss-weak under piss- pfx).

[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 81: All them liquid laughs on the boat have left me feeling weak as piss.
[Aus]J. Alard He who Shoots Last 4: He’s as weak as piss. He ain’t ever pulled a job.
[Aus]M.B. ‘Chopper’ Read How to Shoot Friends 34: ‘Tough Tony’ Franzone wasn’t tough at all. In fact, he was weak as piss.
[UK]Indep. Sport 15 Nov. 7: ‘Weak as piss,’ he calls those without the stomach for the continuing struggle.
[UK]Guardian 15 Dec. 51/4: ‘You’re weak as piss’.
weak in the arm (n.)

see under arm n.