Let me make a simple analogy. Just like a war movie on TV, there is a street code. A Heavenly King Beggars' Sect B Baota Town River Demons use secret codes to determine whether they are one of their own and whether they can give secret things to each other. If the answer is correct, he can give the secret things to the other party. If the answer is wrong, he can kill each other, because he is either a running dog or a traitor.