Thanks to Flashbak for this one:

The Erotic Alphabet of 1880 – All 26 Letters

All 26 illustrated letters from a 19th Century pornographic ABC

Learning your ABCs and working out what each letter stood for became simpler thanks to French artist Joseph Apoux (1846-1910).

In 1880, Apoux gave the world of educational karma sutra his Pornographic Alphabet.

This theme would be later updated in 1971 with a flesh and bone people in a naked human alphabet for Avant Garde Magazine.