Bro, I Found Out the Chief Is Allergic to Rocks

The Giant Stone Tribe has a bizarre rule: no one is allowed to touch stones. The whole tribe believes Chief Tuyan's warning that touching a stone will bring the Mountain God's curse. Ga and Wu may be the only two contrary-minded cavemen around. After carefully observing their surroundings, the brothers with their unusual way of thinking uncover a startling secret:

The so-called curse of the Mountain God is actually just a physical allergic reaction, especially to sharp stones. The chief always keeps as far away from them as he can.

And so, a groundbreaking "treatment plan" is born. They intend to use a piece of flint to help the chief "overcome" the minor health problem that has plagued his family. And, while they're at it, perhaps, maybe, accidentally... change one of the tribe's backward rules.