One day, a student was mischieviously playing with the assistant teacher pencil case.
Student : "Teacher teacher how come you don have any black pen like we all ?"
Student : "You dont need to do any homework ?"
Teacher : "Of course, I do my homework."
* Took out all his red pens from the pencil case *
Teacher : "But I do my homework in red :P"
Teacher : "I mark student homework !!!"