Does anyone else's brain fill in unlikely reasons for unidentifiable noises that intermittently happen around them?
I've just heard the reasonably frequent "someone dragging an empty yoghurt pot on a string along the pavement" noise from outside.
And I may never hear this one again, but my next-door neighbour who recently moved out used to sometimes make this sound that I swear was exactly like she was rolling snooker balls around, up and down, directly on the party wall. I suppose now she's gone, I'll never find out what it was.