Why Parents Have Gray Hair

A father passing by his son's bedroom was astonished to see the bed nicely made up and everything neat and tidy.Then he saw an envelope propped up prominently on the pillow. It was addressed, "Dad". With the worst premonition, he opened the envelope and read the letter with trembling hands:
Dear Dad,
It is with great regret and sorrow that I'm writing you. I had to elope with my new girlfriend because I wanted to avoid a scene with you and Mom. I've been finding real passion with Joan and she is so nice. I knew you would not approve of her because of all her piercings, tattoos, her tight motorcycle clothes and because she is so much older than I am but it's not only the passion, Dad, she's pregnant. Joan says that we are going to be very happy. She owns a trailer in the woods and has a stack of firewood, enough for the whole winter. We share a dream of having many more children.
Joan has opened my eyes to the fact that marijuana doesn't really hurt anyone. We'll be growing it and trading it with the other people in the commune for all the cocaine and ecstasy we want.In the meantime, we'll pray that science will find a cure for AIDS so Joan can get better; she sure deserves it! Don't worry Dad, I'm 15 years old now and I know how to take care of myself. Someday, I'm sure we'll be back to visit so you can get to know your grandchildren.
Your son, Chad
P.S. Dad, none of the above is true. I'm over at Tommy's house. I just wanted to remind you that there are worse things in life than the report card that's in my desk drawer.
I love you! Call when it is safe for me to come home!