"purse-like tegumentary investment of the testes and part of the spermatic cord; the cod" [Century Dictionary], 1590s, from Latin scrotum, probably transposed from scortum "a skin, hide" (see corium), perhaps by influence of scrautum "leather quiver for arrows."
"Isn't the sea what Algy calls it: a grey sweet mother? The snotgreen sea. The scrotum-tightening sea. Epi oinopa ponton." [Joyce, "Ulysses"]