How to answer the funny joke of April 1?

A plane crashed on April 1 day. An China, an American and a Japanese survived, but they fell into an African cannibal tribe and were caught by barbarians. The chief said to the three of them, "as long as the total JJ of the three of you exceeds 20 cm, I will let you go." The three men discussed it and agreed.

Americans are the first, and his is 12 cm. Americans look at the Japanese and China with pride.

Followed by China people, his is 7 cm.

It's the Japanese's turn, and both Americans and China people are thinking, "This kid's is not without 2 cm, is it? My birthday is exactly 2 cm. The chief had to release the three of them.

Americans say, "My contribution is the biggest, more than half of mine."

China people said: "mine is just average, and my contribution is not small."

As soon as my voice fell, I screamed, "If I don't get an erection in time, you are all finished!"