A is for Anus: The Alphabet (For Adults)
This alphabet isn't adult just because A is for Anus, but also because of the accompanying anatomical representation author Max Willy has selected to make sure everyone knows what an anus is. Stick out your pointer finger and say, Tickle, tickle, and I think you'll get what I mean. And that's just the first of 26 lewd and vulgar ways to learn your letters.
Science, geography, and art all get the dirty, dirty, foul treatment in Willy's A Is for Anus: The Alphabet (For Adults). Though obviously not suitable for children, the book is top notch for adults who want to act like them and give someone a gag gift.