How Well Do You Know English Slang?
1590s, alteration of testicule (early 15c.), from Latin testiculus, diminutive of testis "testicle" (see testis). The Old English was herþan, probably originally "leather bag" (cf. heorþa "deer-skin"). The commonest slang terms for them in other languages are words that mean "balls," "stones," "nuts," "eggs."
testicle tes·ti·cle (těs'tĭ-kəl)
A testis, especially one contained within the scrotum.