The Lie Detector ...

One day Tom's dad bought a robot.
The robot was special in that it could detect a lie and would slap the person who lied on the face.
Tom returned late from school that day and his dad asked him, "Son why are you late from school?".
Tom answered, "Dad we had extra classes today".
Much to his astonishment the Robot jumped up and slapped Tom on his face.
His dad told him, this robot is special in that he can detect a lie and will then slap the person who lied now come on tell me the truth, " Why are you late?"
"Dad I went for a movie",
"Which movie?"
"The Ten Commandments",
Splatt... Tom got a tight slap on the face from the robot.
"No dad honest I went for the movie Sex Queen."
"Shame on you son when I was your age I never used to do such shameful things."
Splatt, the dad gets a tight slap on the face from the robot.
Hearing all this, Tom's mother comes walking out of the kitchen saying, "After all he is your son, he will be like you"
The robot steps up and gives a resounding slap on Tom's mothers face.

Dont ask what the moral of the story is ??????????????????????