Chanting at the Asylum

A man walks to work every day. On his way there he always passes the local insane asylum.Well, one day when he was walking by the asylum. He heard all the patients on the other side of the tall wood fence chanting "Fifteen, Fifteen". He became very curious but had no way of knowing what was going on.The chanting became louder "Fifteen, Fifteen, Fifteen" , and his curiosity became stronger. What were they doing? His imagination went wild.... were they torturing fifteen people, were they counting something he did not want to know about? He could not stand the suspense.He finally saw a little knot whole in the fence, just big enough to look through. He walked up to it cautiously and ducked down to look in it.All the sudden he got pocked in the eye with someone's finger. The chanting changed to "Sixteen, Sixteen, Sixteen".