yarbles, n. — Green’s Dictionary of Slang

yarbles n.

[? link to dial. yarb, ‘an opprobrious epithet’ (EDD) + balls n.; popularized by the film A Clockwork Orange (1971)]

1. testicles.

1972		A. Burgess Clockwork Orange 16: Come and get one in the yarbles, if you have any yarbles, you eunuch jelly, thou.
1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: yarbles n. Testicles. attr. A Clockwork Orange.

2. courage, guts.

1974

Eble Campus Sl. Mar. 7: yarbles – fortitude, guts.