A sensor. Someplace. I'm sure of it. I sit down, start typing, really get into a groove, and within seconds either the phone rings, the internet connection craps out, the cats start kvetching, or Noodle wants to show me the new material she's trying out for her bedtime-stalling routine.
I shudder to think what would happen if our doorbell actually worked.
UPDATE: She's added a fourth trip-to-the-potty request. Hoo boy.