What happened on the hunting trip that made Billy feel more grown up?

Billy drank coffee on the hunting trip.... it made him feel all grown up.

I had never been allowed to drink coffee at home and didn’t exactly know what to do. I glanced at Papa. He seemed too busy with his eating to pay any attention to me. Taking the bull by the horns, I reached over and ran my finger through the cup’s handle. I held my breath as I walked over and sat down by a post oak stump. Nothing was said. Grandpa and Papa paid no attention to what I did. My head swelled up as big as a numberfour washtub. I thought, “I’m not only big enough to help Papa with the farm. Now I’m big enough to drink coffee.”