I didn’t copy from Dam

Dam and Tam were in a exam hall. Time was over after 3 hours and both came outside the exam hall.

As soon as they were outside, Tam started to beat Dam.

Teacher saw this and stopped Tam and asked why was he beating Dam.

Dam replied, “During the exam I didn’t know the answer of any question so gave the blank paper. And what he did was, he also didn’t write anything and gave blank paper”

Teacher asked, “So what?”

Tam said, “Since we both have same thing – blank paper, my subject teacher might think that I’ve copied from Dam”