spunghole

All this was done as they did appoint: only Gargantua, doubting that they could not quickly find out breeches fit for his wearing, because he knew not what fashion would best become the said orator, whether the martingale fashion of breeches, wherein is a spunghole with a drawbridge for the more easy caguing: or the fashion of the mariners, for the greater solace and comfort of his kidneys: or that of the Switzers, which keeps warm the bedondaine or belly-tabret: or round breeches with straight cannions, having in the seat a piece like a cod's tail, for fear of over-heating his reins: -- all which considered, he caused to be given him seven ells of white cloth for the linings.

Gargantua and Pantagruel, Illustrated, Book 1 Fran��ois Rabelais 1518