Green’s Dictionary of Slang

chips (and peas) n.

the knees.

1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1981		P. Wright Cockney Dialect and Sl. 105: chips an’ peas ‘knees’.
1998		R. Puxley Fresh Rabbit.
2003		B. Dark Dirty Cockney Rhy. Sl. 38: She must have been desperate. She was down on her chips before I’d got my trousers off.