"Mom " said the boy, "what are all these women doing?"
"They're waiting for their husbands to get off work," she replies.
The taxi driver turns around and says "Geez, lady, why don't you tell him the truth? They're hookers, kid! They have sex with men for money."
The little boy's eyes get wide and he says, "Is that true, mom?"
After a few minutes, the kid asks, "Mom, what happens to the babies those women have?"
"Most of them become taxi drivers!" she said.