One day, when Billy came home from school, his mom 
asked him how his day went. He said, "We're learning 
about sexual education." She smiled, and said, "At 
least he's learning something usefull." Billy went up 
to his room. A little later, Billy's mom went up to his 
room to call him down to dinner. She opens his door and 
sees him jerking off. She says, "Billy, when you're 
done with your homework, supper's on the table."