Son : Daddy, I fell in love & want to date this awesome girl.
Father : That's great son. Who is she?
Son : It's Sandra, the neighbours daughter.
Father : Ohhh I wish you hadn't said that. I have to tell you something son, but you must promise not to tell your mother. Sandra is actually your sister.
The boy is naturally bummed out; but a couple of months later :
Son : Daddy, I fell in love again and she is even hotter!
Father : That's great son. Who is she?
