In which I fall for a practical joke perpetrated by a baby

I'm waiting to cross a street, and this guy pushing a baby in a stroller is waiting next to me. I can't tell how old the baby is - I'd say more than 8 months but less than 2 years.

Suddenly, the baby points skyward and looks up, as though he sees something interesting.  For some reason the father doesn't respond, but I look up to see what the baby's looking at.  However, I don't see anything.  No airplanes, no balloons, no clouds, no birds sitting on a wire, nothing.

So I look back at the baby and say "What do you see?"

And he looks me in the eye and bursts out laughing.

He totally tricked me, and I totally fell for it!