My answer was as ludicrous as you might imagine: "Because that's what sailors did there. ...Or maybe it's called poop because they did it off the poop deck."
So, naturally, while she was brushing her teeth I pulled out my aforementioned Webster's and looked it up. My second guess may still be right. It seems to be derived from the Latin word "puppis," which simply means "the stern of a ship."
I haven't yet studied the history of latrines.
Anyway, farting around in the dictionary, I was - I suppose unsurprisingly - drawn to the definition of "Whiggishness, [n. the quality of being Whiggish.]," which portended a discussion of the philosophy of Whiggism. I was disappointed, of course - it's only a dictionary, after all - but I thought I'd say something about their first and third definitions of Whig:
1. in England, a political party (1697-c. 1832) which championed popular rights and change in the direction of democracy: it later became the Liberal Party: opposed to Tory.
I have no great difficulty there, except that I wouldn't define democracy merely as the ability of the masses to select policy makers or policies of governments with a 50% + 1 vote margin, but rather as the widest possible dispersion of power; which I believe is most effectively promoted by the protection of private property and the right to bear arms.
But definition #3 was of more interest to me:
an American political party (. 1836-1856) opposing the Democratic Party and advocating protection of industry and limitation of the power of the executive branch of government.
On the last clause, I'd argue that the legislative and judicial branches could stand some limiting as well, but I can't fault them for that. But I do fault them for their stand on "protection" of "industry." What they meant was high tariffs and limiting competition for established businesses: the use of the power of government to create and defend monopolies.
I'm all for protecting industry, as in "...intelligent work; skill; cleverness..." or an application thereof. You do that by protecting property rights, but the American Whig Party meant to protect industries, and, since they believed in wielding the power of government to do it, they didn't recognize the government's limited ability and it's need to pick and choose.
I need more time. We're coming up on midnight here.