chuckies, n. — Green’s Dictionary of Slang

chuckies n.

[pun on balls n. (1)/SE balls, which one can ‘chuck’; note Scot. chuckies = stones, thus link to stone n.¹ (1)]

testicles.

1973		(con. mid-1960s) J. Patrick Glasgow Gang Observed 76: More butts with the head and ‘boots in the chuckies’.
2000		Roger’s Profanisaurus 🌐 chuckies n. Balls.