While stumbling about (but not Stumbling*), searching for the origin of the word “nincompoop,” I came upon an entry in Micheal Quinion’s World Wide Words (see blogroll). Of course, we understand that “nincompoop” refers to “a foolish or stupid person,” but Mr. Quinion’s exploration of others’ accounts for the word is worth perusing.
After examining Dr. Johnson’s and John Ciardi’s explanations, Mr. Quinion settles on one from the Oxford English Dictionary:
A more intriguing idea, one with a fair level of acceptance that is given with some caution in the current revision of the OED, links it with the given name Nicodemus, especially the Pharisee of that name who questioned Christ so naively in the Gospel of St John. This word still exists in French as nicodème, a simpleton.
Read Mr. Quinion’s entire entry.
* I wasn’t using http://stumbleupon.com/.