I was trying my best to answer the neighbours daughter as she came out with the longest stream of questions I’ve ever heard anyone have about an oil filled radiator. Skirting around Specific Heat Capacities and Conservation of Energy[1] (but laying the foundations, should she ask later), things don’t quite finish as I planned:

H: Why is it wet ?
Me: Because the radiator has been outside in my car and the metal is below the dew point of the room, so now that it’s been brought back inside the water vapour in the air is condensing on the surface.
H: Do you have a Grandma and Grandad ?
Me: I’ve run out of Grandad’s but I have two Grandma’s
H: You don’t have any Grandad’s ?
Me: No
H: How do your Grandma’s stand up then ?

I guess you simply can’t outsmart them, even by trying to come up with such detailed explanations that the Why? game ceases to be attractive: they just go and channel Spike Milligan instead…

[1] No, I’m not slacking, but the Muppets were on. There’s only so much Physics that can be talked when faced with option of watching Gonzo and a chicken or two…