"you don't have kids so you wouldn't understand"

I was handed a piece of paper with this joke.

A man is packing for a trip while his daughter plays on the bed. "Daddy look at this!" she says while holding up her finger. To keep her entertained, he says "Daddy's gonna eat your fingers" and puts her little fingers in his mouth. The girl looks confused and says "where's my booger?"

I handed it back and said it was gross.

Then I was told that I don't have kids, so I wouldn't understand.

Questions:
1- you knew I didn't have kids, so why did you hand it to me?
2- you don't have kids either.
3- since you knew I wouldn't understand, why didn't you explain it to me?
4- what happened to the booger, and what does it have to do with the rest of the story?
5- why are you wasting my workday, making me try to figure this out?