A very recent conversation in the M-P household.
"how does Father Christmas fit down the chimney?"
(oh boy, here we go...)
"erm... it's magic"
*indignantly* "there's no such thing as magic! So how does he do it?"
"well," said (proud) father, "you don't realise it yet, son, but you've just answered your own question."
at which point Ronwen stepped in and started talking about the special skeleton key that Santa uses to get into houses with no chimneys.