A cop drives up Lovers' Lane and sees a car parked. He walks up to the car and sees a girl in the back seat knitting and a boy in the front seat reading a book.
The cop asks the boy how old he is and what he's doing. The boy answers, "I'm reading a book, and I'm 20."
Then the cop asks what the girl's doing and how old she is. The boy replies, "She's knitting, and she'll be 18 in about five minutes."