Green’s Dictionary of Slang

knackers n.

also knacks, nackers, nakers
[dial.]

1. the testicles.

[UK]‘Judy’s Got a Rare Black Eye!’ in Ri-tum Ti-tum Songster 22: In silent bliss mankind reposes; / Her hands upon our knackers prest.
T. Edmondston Etym. Gloss. Shetland and Orkney Dial. 76: Nackers, testes, S .
in E. Peacock Gloss. Words Manley and Corringham, Lincolnshire .
[UK]Barrère & Leland Dict. of Sl., Jargon and Cant I 523/2: Knackers [...] (Butchers, &c.), the testicles, also ‘knuckers’.
[Ire]Joyce Ulysses 549: Eh, Harry, give him a kick in the knackers.
[UK]J. Curtis There Ain’t No Justice 142: Lay off of that. You’re spieling knackers.
[UK]J. Curtis They Drive by Night 115: ‘You better arst the sergeant.’ ‘He’ll chew my nackers off.’.
[US] in G. Legman Limerick (1953) 245: There was a young man of Malacca / Who always slept on his left knacker.
[UK]P. Larkin letter 30 July in Thwaite Sel. Letters (1992) 166: The absurdity of it all struck me like a fist in the knackers – like trying to argue away the sun.
[UK]N. Dunn Up the Junction 40: ‘Aren’t Chelsea blokes sexy?’ ‘No [...] They lost their knackers in the Flood.’.
[Aus]K. Gilbert Cherry Pickers III ii: (Grabs at toodle’s crotch) How’s ya bunions? [...] How’s yer knackers?
[UK](con. 1939) J. Rosenthal Evacuees Scene 39: It’s not swearing. ‘Nackers’ is swearing.
[Aus]D. Ireland Glass Canoe (1982) 225: Someone lurched above me, tried to recover balance and trod fair on my knackers.
[UK]B. Chatwin Songlines 79: ‘Not bad for seventy-three!’ he looked down at himself. ‘Serviceable knackers!’.
[Ire](con. 1920s) L. Redmond Emerald Square 73: We had often thought up tortures for Yella’ Man. Such things as hanging him up on a butcher’s hook by the nakers.
[Aus]Penguin Bk of More Aus. Jokes 379: Do you know your knackers are hanging through the old wicker chair?
[UK](con. 1977) D. Peace Nineteen seventy-seven 11: He tuts and scratches his knackers as he gets out of the car.
[Aus]P. Carey Theft 20: We did the old charge and grab the knackers.
[UK]S. Kelman Pigeon English 213: I’d kung fu him in the knackers.
[Aus]N. Cummins Tales of the Honey Badger [ebook] [T]hat little bastard [...] went straight at the big prick’s nutsack and ripped his knackers clean off.

2. in fig. sense, courage, synon, with balls n. (3)

[UK]T. Black Gutted 118: They’ve still got the knackers to fight for their country.

In phrases

off one’s knackers

insane, stupid.

[UK]Observer Mag. 21 May 26: That this world’s for real. That if you’re bored, you’re off your knackers.

In exclamations