A kid asks his father for help on a writing assignment. "Dad, can you tell me the difference between potential and reality?"
His father looks up thoughtfully and says, "I'll demonstrate. Go ask your mother if she would sleep with Robert Redford for a million dollars. Then go ask your sister if she would sleep with Brad Pitt for a million dollars. Come back and tell me what you've learned."
The kid is puzzled, but asks his mother. "Mom, if someone gave you a million dollars, would you sleep with Robert Redford?"
"Don't tell your father, but, yes, I would."
He then goes to his sister's room. "Sis, if someone gave you a million dollars, would you sleep with Brad Pitt?"
She replies, "Omigod! Definitely!"
The kid goes back to his father. "Dad, I think I've figured it out. Potentially, we are sitting on $2 million bucks, but in reality, we're living with two sluts."