A blonde teenage girl comes home from school and asks her mother, "Is it true what Rita just told me...

...that babies come out of the same place where boys put their thingies?"

"Yes, dear." Replies her mother, pleased that the subject had finally come up and she wouldn't have to explain it in so much detail to her daughter.

"But then when I have a baby," responded the blonde teenager, "won't it knock my teeth out?"