Why ask Why?

Willa's current favorite question - "why?"  She may ask this between 10 and 200 times a day.  Sometimes 5 or 6 times in a row.  Often, it is unclear what the "why" even refers to.  If she wasn't so adorable, could be awfully annoying.  Ethan has taken to answering "beacause, the end," which he learned from Karri.