Here's your nightmare image for the day: the front cover of SHIGUREAN Asui's 1889 collection, Senryū neko-namazu: Kokkei hokku yanagidaru (しぐれ庵蛙水, 川柳猫鯰滑稽発句やなぎ樽), or "Cat and Catfish Senryū: A Willow Barrel of Humorous Hokku."

The first ass gag (doubling as the first woman gag) appears on the very first page:

細君とちと言にくい尻のはゞ

"Hard to say the 'little woman'/ when her ass is that wide." Charming. Passing over the unplanned pregnancy-related thighslapper on the same page, we find the first fart gag on page 2:

尻と顔両方へ出るむすめの屁

"By ass and face alike revealed:/ A young lady's wind." This is exactly the kind of thing that made Kenneth Rexroth so cross.