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, Johnny's 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 Mommy's balloons and she's screaming, "Oh God, I'm coming!"