From dictionarydotcom:
topknot
1. a tuft of hair growing on the top of the head.
2. hair fashioned into a knob or ball on top of the head.
3. a tuft or crest of feathers on the head of a bird.
4. a knot or bow of ribbon worn on the top of the head.
I watched Anna and the King a couple of weeks back (yes, I'm behind the times, still haven't seen all the episodes of a barely-remembered 60's soap opera, let alone movies from the past decade) and all the little Siamese children had topknots, with circlets of pearls (or something) around them. Might have been sort of cute on Bruno.
Back to the original topic: I watched the infamous episode 766 a week ago, before the stairless scene had been isolated, and didn't noticed the lack of stairs. Watched it again yesterday, and there it was - or, rather, there it wasn't. It's wonderful what gaps your mind will fill in for you. I did notice, a week ago, that the sound in the Old House living room seemed more cavernous than usual - but that's as far as I got.