The context of the following conversation is Kai had made a promise to his friend and crossed his heart and hoped to die.:
Kai says I promised that I wouldn't tell anyone what she said..
The friend responds Well what did she say?.
Kai responds I can't tell you! I crossed my heart and hoped to die. I can't betray her trust..
The friend responds I understand. I was joking, it is good you are so loyal..
Kai responds I just wouldn't want someone to betray me..
The friend responds Me neither. You are a good friend..