According to Wikipedia, one theory for the etymology of くノ一 (female ninja) is that it's made up of the strokes of the kanji 女 (woman).
Other theories include that it means nine and one, talking about the number of orifices men and women have, and yet another is that the term くノ一 is apocryphal. Finally, this page suggests that くノ一 might be "real", but is just a code word used by ninjas to mean woman, rather than meaning female ninja.
Are there any other words, historical or present, where the characters are made up of strokes of a kanji, along the lines of the 女 etymology theory for くノ一?