Conversation. Again

It's the morning and we were getting ready to send Ameera to the bus stop for school. While putting on Hisham's jacket suddenly, Ameera asked me.

Ameera: Mummy can we go by car today...?
Mummy: Of course. Yes.

Suddenly, Husayn who was entertaining himself, shouted out.

Husayn: Yay! Yay! We're going by car! (turning the words into his own improvised song)

I was confused as to why he was so excited.

After dropping Ameera off, we arrived back home. When opening the car door for Husayn...

Husayn: Mummy, I thought we're going by car? (half whining and looking extremely disappointed)
Mummy: Yes, we did send Ameera by car.
Husayn: Nooooo. You said we were going BY CAR!!!
Mummy: We did.
Husayn: Nooooo. You said we're going to BUY a car? Where is the new CAR???
Mummy: ?????

After a good 10 minutes explaining it to him he eventually understood and stopped crying. We're going to send Ameera with a car instead of walking.

Husayn: OoOoOOoh!

At the bus stop waiting for Ameera