Lewis & Short

2. testis, is, m., a testicle, Plaut. Mil. 5, 28; 5, 33: dexter asini testis in vino potus, Plin. 28, 19, 80, § 261: testes pecori ad crura decidui, id. 11, 49, 110, § 263; so in plur., Lucil. ap. Non. 235, 5; Hor. S. 1, 2, 45.
In a pun, with 1. testis: quod amas, amato testibus praesentibus, Plaut. Curc. 1, 1, 31: magnis testibus ista res agetur, Auct. Priap. 2: cf. integritatis, Phaedr. 3, 11, 5.