in a public place, then looks up and and smiles what do you do? Do you smile back, wave hello, ignore them, or what?

I say hello and wave back. No need to make kids jaded right out of the gate.

smile back

let me get a high five little man

I always smile back and wave at them...nothing is more precious than a smile or laugh from a child

I smile back. Then I steal his candy and run like hell.

Aww... I totally smile back.

smile back

Smile, wink, make funny faces, I always get busted by the adults!

I offer them candy and tell them it is in my van.

No i usually just smile, make a funny face and wave back.

Dude

I kick em in the ass and tell em, "Keep walkin', Junior!".

Smile of course. Don't want to scare the little tyke.
I love children.............. if properly cooked.

I love kids I always say hi back!

nothing before but now i smile and laugh with them

Definately wave... but be careful... you might get arrested for being a pedophile

I always respond. I just can't help myself. They are so cute!

I always smile back and say hi if their parent doesn't mind.

I make growly-growly noises and chase after them like I'm a monster or a lunatic. Not only will they get their exercise (in running away from me), but they'll also learn a valuable lesson... don't trust strangers).

I smile at them and then of course they start to cry.