A teacher instructs her fifth-grade class to ask their parents to tell them a story with a moral at the end.
The next day the kids come in and share their stories. After a few students tell their stories, the rest of the class learns some of the morals you'd expect to hear, such as "don't count your chickens before they hatch" and "treat others as you'd like them to treat you."
Then it was little Timmy's turn...
"My daddy told me about my uncle Dave," says Timmy. "He was a pilot in Vietnam and had to bail out over enemy territory with nothing but a flask of whiskey, a pistol, and a knife. He drank the whiskey during the drop, then landed in the middle of 20 Charlies. He shot 15, stabbed three, and killed the last two with his bare hands."
"What is the moral of that horrible story?" yelps the mortified teacher.
"Stay away from Uncle Dave when he's been drinking."
