Homework with a lesson

The teacher tells the kids that in their homework they have to write a family story with a lesson in it.
The next day:
"Okay, Jack, what is your family story?"
"Once we went to the fair to sell some eggs. We put them in a basket, but mom accidentally dropped the basket and all the eggs broke."
"And what is the lesson in your story?"
"Don't put all the eggs in one basket."
"That is a good story. So, Jane, what is your story?"
"Once we too went to the fair but we decided to sell milk. We put the milk in a kettle, and we put the kettle on a horse. The horse tripped, the kettle fell, and all the milk spilled onto the ground."
"And what is the lesson in your story?"
"Don’t put all your milk in one big kettle."
"That is a good story too. And now Joe, what is your story?"
"My uncle Bob was a Green Beret in Vietnam. Once his helicopter got shot down. As the helicopter was falling he put his knife into his belt, grabbed a machine gun with all the ammo he could find near by and he drank the last bottle of whisky, so it does not break and go to waste. Then when the helicopter crashed, and he was getting out of the wreck, he saw a hundred very hostile Vietcong approaching him. He mowed down 60 with his machine gun, but he run out of ammunition, then he killed another 30 with his knife but it went dull, so he had to kill the last 10 with his bare hands."
"Oh my god, Joe, and what was the lesson of this horrible, horrible story?"