What does Peeta mean when he says, "Well, they've already promised to do that to us anyway,"?

When Haymitch discusses with Peeta and Katniss about the possible consequenses of her display of rudeness in front of the Gamemakers, he says, "Most likely they'll make your life hell in the arena.", to which Peeta replies, "Well, they've already promised to do that to us anyway,". Where in the book have the Gamemakers promised to make life hell for them in the arena, and is this promise specifically directed towards Katniss or the tributes in general?