"Lie Like Your President" joke

DAD - Son, come in here, we need to talk.
SON - What's up, Dad?
DAD - There's a scratch down the side of the car. Did you do it?
SON - I don't believe; if I understand the definition of "scratch the car"; that I can say, truthfully, that I scratched the car.
DAD - Well, it wasn't there yesterday, and you drove the car last night, and no one else has driven it since. How can you explain the scratch?
SON - Well, as I've said before, I have no recollection of scratching the car. While it is true that I did take the car out last night, I did not scratch it.
DAD - But your sister, Monica, has told me she saw you back the car against the mailbox at the end of the driveway, heard a loud scraping sound, saw you get out to examine the car, and then drive away. So again I'll ask you, yes or no, did you scratch the car?
SON - Oh, you mean you think you have evidence to prove I scratched it. Well, you see, I understood you to mean did "I" scratch the car. I stand by my earlier statement, that I did not scratch the car.
DAD - Are you trying to tell me you didn't drive the car into the mailbox?
SON - Well, you see sir, I was trying to drive the car into the street. I mishandled the steering of the car, and it resulted in direct contact with the mailbox, though that was clearly not my intent.
DAD - So you are then saying that you did hit the mailbox?
SON - No sir, that's not my statement. I'll refer you back to my original statement that I did not scratch the car.
DAD - But the car did hit the mailbox, and the car did get scratched as a result of this contact?
SON - Well, yes, I suppose you could look at it that way.
DAD - So you lied to me when you said you did not scratch the car?
SON - No. No, that's not correct. Your question was "Did I scratch the car?" From a strict legal definition, as I understood the meaning of that sentence, I did not scratch the car... the mailbox did... I was merely present when the scratching occurred. So my answer of "No" when you asked "Did I scratch the car" was legally correct, although I did not volunteer information.
DAD - Where in the heck did you learn to be such a liar?
SON - From The President of the United States.