The professor collects the students’ homework:

Toto says to his friend John:

• • Thank you John, one more homework not done, and the professor was going to call my parents!
  • Yup. I don’t really like this. I hope you did not copy word-for-word?
  • You can be certain that I copied everything to perfection! and when I say everything, I mean everything!

The professor returns the homework, looks, and all of a sudden says:

• Toto, how come I do not have your homework? and how come I have two copies from John?