I ALREADY KNOW

There is a New Student (NS) and Old Students (OS) were chatting during physics lessons.


OS: "Hi, you are a new student right?"
NS: "Yes .."
OS: "Be careful you are with the Physics teacher, if one could at least slap"
NS: "Ooh ... I already know"
OS: "Yeah, it's a bad teacher, so his face like beggars, poor again!"
NS: "Ooh ... I already know"
OS: "Just NSout when to go home, we teased him okay! we flush the sewer water use, if 
         necessary, we beat you that bad teachers! by the way, how come you had been told if you 
         already know anyway? "
NS: "I was his son!"