Green’s Dictionary of Slang

flake n.2

[flaky adj.]

1. (orig. US, also flakeout, flako) a boring, unappealing, incompetent, undesirable person.

[US]R. Russell Permanent Playboy 251: What honesty! What frankness! You’re no flake, Taddie.
[US]J. Blake letter 19 Mar. in Joint (1972) 178: I am not a chronic flakeout, let it not be said that I let the team down.
[US]Current Sl. IV:1 7: Flake, n. A dumbell; one who is not very bright.
[US]C. McFadden Serial 32: He’d taken up with a woman he’d always said he thought was a total flake.
[US]S. King It (1987) 793: Just the fact that Henry let a flako like Patrick Hocksetter hang around.
[Aus]C. Bowles G’DAY 89: Ardunno. Think I'll take a rain check. Reckon e’s a bit of a flake.
[US]C. Hiaasen Skin Tight 185: The guy was a flake, but who cared.
[US]D. Burke Street Talk 2 17: What a flake!
[US]F.X. Toole Pound for Pound 294: You turn out to be a flake [...] you’re outta here.
hubpages.com ‘Roadman Slang 4 Jun. [Internet] Flake - an unreliable person that ‘flakes’ on any agreed plans.

2. (US) an eccentric, crazy person.

[US]Time 9 Feb. 34: For kicks, Killy races fast cars and jumps from airplanes; he has tried his hand at bullfighting, and he has a well-deserved reputation as something of a flake.
[US]H. Ellison Flop Sweat in Shatterday (1982) 67: This flake does a good enough job scaring the hell out of me on his own.
[US]C. Hiaasen Tourist Season (1987) 61: He’s also a card-carrying flake.
[US]Eble Campus Sl. Oct. 1: art flake – one who fancies himself or herself very artistic.
[UK]Z. Smith White Teeth 32: An assorted company of Hippies, Flakes, Freaks and Funky Folk.

3. (US) a disappointment or failure.

[US]‘Paul Merchant’ ‘Sex Gang’ in Pulling a Train’ (2012) [ebook] Pinch babe with his lech for little girls [...] That working broad was going to have some nights that wedre real flakes.
[US]H. Ellison ‘Memory of a Muted Trumpet’ in Gentleman Junkie 107: Spoof was feeling down. The party was a flake.
[US]N.Y. Times 20 Oct. 36: A flake [...] is the arrest, on known false evidence, of a person for something he did not do.
[UK]F. Taylor Auf Wiedersehen Pet Two 49: You don’t have to worry about your Barry. Sound as a bell, he is. I’m a bit of a flake.

4. a worthless or second-rate type.

[US]R. Shell Iced 210: If [...] you should find a flake of a job while waiting for your next hand-to-mouth-out [...] they bleed you.