Kids do say the darndest things

So I was in between flights at the Seattle airport, brushing my teeth in the bathroom and generally minding my own business when a little boy (6 or 7) came up to me.

boy: what are doing?

me: brushing my teeth

boy: why are you brushing them?

me: to keep them clean

boy: but in a public bathroom?

me: that's because i'm not at home

boy: oh ok

Well that seemed to be sufficient explanation for him but it makes me wonder how many adults wonder but just don't ask...