"Why is a raven like a writing desk?" The answer Lewis Carroll gives is that "They both produce a few notes, all very flat, and are almost never turned the wrong way front."
or is it
"Because the notes for which they are noted are not noted for being musical notes"
"Because Poe wrote on both."
or maybe it's because
"Both have inky quills."
or the obvious
"because there's a B in both, and there's an N in neither."