kaa kaa

All vehicles, in Nischal's mind, are a variant of 'kaa'.
Its either 'kaa' or 'kaa kaa'

He points to pictures of buses, cars, tractors, etc. wherever he can find, and smile at you and say 'kaa' or 'kaa kaa' with a lot of enthusiasm.

So his dad set out to teach him.
He would point at a bus and say 'bus' . Nischal would smile at him, and say 'kaa kaa'

Dad would smile a " I'm not giving up with you yet" smile, and repeat 'bus'. Nischal would also smile indulgently while saying back 'kaa kaa'.

This back and forth went on for a while.

Dad kept wondering why his son wasn't learning. Then he tried to see logic in Nischal's uttering. 'kaa' for a car, and 'kaa kaa' for a bus seemed kind of right.
Finally, dad said 'kaa kaa'.

Nischal smiled with relief. Teaching this dad of his was turning out to be real hard!