Not — so not — making this up. From the Village Voice (popup warning):

It is a truth universally acknowledged that Everything Is Funnier With Monkeys. If J. Fred Muggs, Lancelot Link, or zoo-house fecal tossing have taught us anything, it is that every human endeavor is enriched by the addition of a screaming, leg-humping, ass-biting primate. Even, say, sex education. I beg your pardon? you might ask. Clearly you’re not acquainted with the strangest children’s book of the 19th century Sammy Tubbs, the Boy Doctor, and Sponsie, the Troublesome Monkey (1874).

It’s a Victorian sex-ed manual. For children. Starring a monkey.