What is the origin of the trap door in long underwear?

Question: What is the origin of the trap door in long underwear?

Answer: In 1910, the Cooper Underwear Company addressed one of the greatest clothing conundrums of the day -- the union suit, which was the standard for men's underwear. This single undergarment covered the wearer from wrist to ankle, keeping him warm in the days before central heating. Unfortunately, a trip to the bathroom or out-house meant totally disrobing, a somewhat vexing undertaking. To solve this problem, the Cooper Underwear Company introduced a revolutionary garment: the Kenosha Klosed Krotch, a union suit with two pieces of the body fabric lapped over each other like an "X." When the wearer needed to use the opening, this lap could be drawn apart, eliminating the need to totally undress. Incidentally, this company is very much in existence today as Jockey International, Inc.