Who can give me a cold joke? Be short, pithy and super funny!

Father and son are sleeping. They hear the newlyweds making a lot of noise next door. Because the sound insulation effect is not good, the son asked, "Dad, what is this noise?" Dad calmly replied: "this is Japanese, you will understand when you grow up!" " "

The art teacher asked the students, "Why hand in a blank sheet of paper?" . The student said, "I drew it! I painted cows eating grass. " The teacher asked, "What about the grass?" He said, "It was eaten by a cow." The teacher asked, "What about the cow?" He said, "Eat the grass and go."