When someone jokes that they promise each other, how is the best way to answer the question?

When someone calls to make a promise, what is the best answer? You know someone is joking with you, so you always joke according to this sentence. You said you could kill yourself, but I can accept it unconditionally, as long as you are happy and willing. This is also a joke you played on him. In another way, I really dare not take it, because I can't afford it, and I dare not take it, because I also hope that if you really like me and love me, I will take it.