"Little Johnny" joke

Little Johnny is taking a shower with his mother and says, "Mom, what
>are those things on your chest!?" Unsure of how to reply, she tells
>Johnny to ask his dad at breakfast tomorrow, quite certain the matter
>would be forgotten. Johnny didn't forget. The following morning he
>asked
>his father the same question. His father, always quick with the
>answers,
>says, "Why? Johnny, those are balloons. When your mommy dies, we
>can blow them up and she'll float to heaven." Johnny thinks that's neat
>
>and asks no more questions.
>
>A few weeks later, Johnnys' dad comes home from work a few hours early.
>
>Johnny runs out of the house crying hysterically, "Daddy! Daddy!
>Mommy's
>dying!!"
>
>His father says, "Calm down son! Why do you think Mommy's dying?"
>
>"Uncle Harry is blowing up Mommys' balloons and she's screaming "Oh
>God,
>I'm coming!"
>
>