Green’s Dictionary of Slang

1. in pl., the testicles.

1664

C. Cotton Virgil Travestie (1765) Bk IV 88: Ta’en his Knife, and in that Passion / Whipp’d off his Tools of Generation.

2. the penis (cf. instrument n. (1b)).

1734

C. Johnson Hist. of Highwaymen &c. 143: He pulled his Generation Tool out of his Breeches.