Green’s Dictionary of Slang

grollies n.

testicles.

2000		N. Griffiths Grits 224: Thair’s a hole in the crotch uv is shorts and [...] a catch a glimpse of is grollies, all shrivelled like walnuts.
2006		D. Mitchell Black Swan Green 361: ‘Crotch rot.’ Squelch shoved one hand down his pants and gave his grollies a good scratching.