What is that called?

Little Bear is in that toddler stage where he questions what everything is.
He points at random things or people and asks 'What is that called?'.
So it goes like this ..
Scene - we are driving down a suburban road
Little Bear: 'What is that called?' (pointing out the window)
Me (thinking he means the dump truck because I'm driving and don't have eyes at the back of my head): Thats a dump truck ..
...silence for 1 second. We have passed the dump truck ..then ..
Little Bear: 'What is that called?'
Me (guessing): thats a car..
Little Bear: what is that called?
Me (clearly I have no idea what he means): thats a car ...
Little Bear: what is that called?
Me: no response
Little Bear.frustration in voice ..what is that uncle called?
Me: Oh! the uncle? I don't know his name ..Its just uncle..
And so it goes ....

DH says he is intellectually curious. The pessimist in me thinks its a little early to say that.