a hole in the floor about a foot across

"The toilet on the train looked as though a child had designed it, too. It was a hole in the floor about a foot across. Well, I had seen squat toilets before; but this one was traveling at about fifty miles an hour through the ice and snow of northern China. There was no pipe or baffle. If you looked down you saw ice streaking past. A gust of freezing air gushed out of the hole. Anyone fool enough to use this thing would be frostbitten on a part of the body that was seldom frostbitten. And yet the passengers trooped into this refrigerated bum-freezer. When they came out their eyes were tiny and their teeth were clenched, as though they had just been pinched very hard."

~~ from Riding the Iron Rooster: By Train Through China by Paul Theroux