Green’s Dictionary of Slang

spaz n.

also spas, spasmo, spasmoid, spass, spazz, spazzer, spazwit
[SE spastic, one who suffers from spastic paralysis, i.e. ‘a condition in which some muscles undergo tonic spasm (sometimes resulting in abnormal posture) [...] so that voluntary movement of the part affected is difficult and poorly co-ordinated’ (OED); abbr. spastic n.]

1. a spastic.

[US]The Elastik Band ‘Spazz’ [lyrics] I said, get offa the floor, get offa the floor, boy, people gonna think, yes they’re gonna think, people gonna think you’re a spazz.
[UK]Guardian G2 6 Jan. 5: Surely Sheringham cannot be doing what I believe is called [...] a ’spaz’ impression.

2. (student/school) one who is useless, clumsy, incompetent and is thus socially unacceptable; thus hyperspazz, spaz attack, a state of excitement.

[US] J. Fineman journal cited 25/06/05 ADS-L [Internet] SPAZ, n. [Regional] (shortened from spastic) 1. Obsolete. A person lacking in the common social skills & virtues. See TWITCH.
[US]Current Sl. II:3 10: Spass, n. An uncoordinated person (from spastic). [Ibid.] II:4 9: Spaz attack, n. An upset, excited condition.
[Aus]Aus. Women’s Wkly 3 Apr. 58/3: ‘Like, my art teacher is a spaz.’ ‘A spaz?’ ‘Hopeless, a wipe-out’.
[US]G. Underwood ‘Razorback Sl.’ in AS L:1/2 67: spas n 1: Uncoordinated, clumsy person 2: Person regarded as dull, foolish, or stupid.
[US]J. Sayles Union Dues (1978) 103: The old man has been a total spaz since the year one, the coordination of a five-year-old.
[US]S. King It (1987) 147: He was a spasmoid, but I loved him.
[Aus]T. Winton That Eye, The Sky 80: He doesn’t look like a spaz.
[US]Eble Campus Sl. Apr. 5: Bill had a hyperspazz when he found out that his car had been totaled.
[UK]Fraser & Meadows TwentyFourSeven [film script] (1998) 84: Oh bollocks. His room’s at the back, you spazz.
R. Twigger Angry White Pyjamas 265: Paul thinks you’re a spaz.
[UK]J. Poller Reach 35: For the next three years all I seemed to hear were jubilant cries of ‘spas’ or ‘spasmo’.
OnLine Dict. of Playground Sl. [Internet] spack, spaz, spazmo, spacker, spanner, spadge n. [...] An excessively stupid or unpleasant person.
[UK]M. Haddon Curious Incident of the Dog 56: People used to call [...] the children at school spaz and crip and mong.
[UK]D. Mitchell Black Swan Green 292: Right spazzers we must have looked.
[UK]S. Kelman Pigeon English 33: We weren’t talking to you, spaz.
[UK](con. 1980s) I. Welsh Skagboys 82: Ah’d rather be stuck wi the lassies than these fuckin spazwits.

3. (US campus) a general pej.; no physical incompetence is implied.

R. Baker in N.Y. Times 11 Apr. E14/6: Your teen-age daughter asks what you think of her ‘shades,’ which you are canny enough to know are her sunglasses, and you say, ‘Cool,’ and she says, ‘Oh, Dad, what a spaz!’.
P. Kael I Lost it at Movies III 259: The term that American teen-agers now use as the opposite of ‘tough’ is ‘spaz’. A spaz is a person who is courteous to teachers, plans for a career [...] and believes in official values. A spaz is something like what adults still call a square.
[US]Eble Campus Sl. Fall 3: CRACK-WHORE – person unworthy of respect or esteem [...] Also SPAZ.

In derivatives

spazzy (adj.)

1. (also spazzed) stupid, uncontrolled, bizarre, intense, nervous (cf. spazzled adj.).

[US]P. Munro Sl. U. 178: spazzy energetically weird, hyper.
[US]Eble Campus Sl. Mar. 9: spazzed – tense and uptight.
OnLine Dict. of Playground Sl. [Internet] spack, spaz, spazmo, spacker, spanner, spadge n. [...] An excessively stupid or unpleasant person. (also adj. spasticated, spazzy, spazzed).
[UK](con. 1980s) I. Welsh Skagboys 110: Ma Auntie Alice wis lookin eftir spazzy Wee Davie.

2. good, wonderful.

[UK]I. & P. Opie Lore and Lang. of Schoolchildren (1977) 181: Other superlatives in favour were: [...] snazzy, and spazzy (used particularly of costume).

3. lit. spastic or disabled.

[UK]I. Welsh Filth 374: Bruce Robertson, the Cripple Shagger! Whaire’s yir wee spazzy bird the day?

In compounds

spaz pads (n.)

orthopaedic shoes.

[US]S. Morgan Homeboy 268: Sunny [...] recognized them for what they were, spaz pads.
spaz-wit (n.)

a fool, an idiot.

[UK]I. Welsh Filth 7: I know that spazwit’s crack; the bastard wants to be a fuckin scriptwriter.
[UK]I. Welsh Glue 90: How can they say Manchester United’s a Fenian team? Fuckin spazwits.

In phrases

chuck a spaz (v.)

(Aus.) to lose one’s temper.

[Aus]G. Seal Lingo 104: Parents may be requested not to chuck a spaz when remonstrating with some less than satisfactory aspect of their adolescent offspring’s behaviour.
[NZ]McGill Reed Dict. of N.Z. Sl. 47: chuck a mental/spaz/wobbly Lose temper or behave erratically.