Before we even meet Augustus Gloop, we know what he's all about. He's described as "enormously fat" (6.1) and his mom doesn't help his case when she tells the reporters just how much chocolate he eats.
Honestly, he doesn't do much other than eat. And eat. The first thing he does when he gets inside the Chocolate Room is pick up a big handful of sugar grass to eat, while everyone else just takes one blade (15.10). And what does he do next? Take giant gulps from the chocolate river, of course. Big mistake.
Because of how early on he gets taken away from the tour, he doesn't get much chance to say anything. In fact, he says a grand total of eighteen words the whole time, and a third of them are "Help! Help! Help! […] Fish me out!" Poor guy.
But if you think about it, the most important thing about Augustus isn't what he says, but what he hears, and chooses not to listen to. The parents – and Willy Wonka – warn Augustus over and over again not to drink from the chocolate river. But he, like all the children after him (except Charlie, of course), just won't listen. And he, like all the children after him, pays the price.