What is Ralph's act of rebellion against civilization?

This question seems to indicate that Ralph has a single act of rebellion against civilization, and I do not agree with that. I think Ralph does a fair number of things that rebel against civilization. While I don't think that Ralph ever becomes as savage as Jack, I do think that he feel stifled by adults and the rules that govern him in civilized society. I think the first rebellious act that he does can be found in the first few pages of the book: he and Piggy have been discussing their situation, and Ralph comes to the beach. Something about it overpowers any of his thoughts of societal impropriety, and he strips completely naked and runs into the water.

He jumped down from the terrace. The sand was thick over his black shoes and the heat hit him. He became conscious of the weight of clothes, kicked his shoes off fiercely and ripped off each stocking with its elastic garter in a single movement. Then he leapt back on the terrace, pulled off his shirt, and stood there among the skull-like coconuts with green shadows from the palms and the forest sliding over his skin. He undid the snake-clasp of his belt, lugged off his shorts and pants, and stood there naked, looking at the dazzling beach and the water.

Notice how the island has already made him aware of the weight of his clothes. He is tied down and burdened by that weight and strangled by the elastic garter and belt. His first rebellious act is casting off all of the clothes that a civilized society would make him wear.

One can argue that Ralph's participation in Simon's brutal death is considered a rebellion against civilization. For the majority of the story, Ralph is a proponent of civilization and attempts to establish a civil, organized society on the uninhabited tropical island. Unfortunately, Jack undermines Ralph's authority and ends up establishing his own tribe of savages on the far side of the island. Despite Ralph's efforts to maintain order and promote civilization, he also momentarily descends into savagery. In chapter 9, a severe tropical storm hits the island, and Ralph joins the group of boys, who participate in a ceremonial dance. As the storm increases in intensity, the boys work themselves into a frenzy. At the height of their ritual, Simon stumbles onto the beach, and the boys mistake him for the beast. One could argue that Ralph "rebels against civilization" by participating in Simon's brutal death. Along with the other boys, Ralph savagely rips, bites, and tears at Simon until he dies on the beach. Ralph's momentary lapse of civility is one of the only times he completely dismisses civilization.