What is the conflict in chapter 20?

In chapter 20 of Holes, Mr. Sir brings Stanley to see the Warden. Mr. Sir's sunflower seeds have been stolen, and although he doesn't think that Stanley was responsible, he does believe that Stanley is covering up for the perpetrator. The Warden is not exactly thrilled at being disturbed over what she considers such a trivial matter. She's a fearsome woman to both kids and overseers alike, as she proceeds to demonstrate when Stanley is brought before her.
She asks him to go into the next room and bring back her small makeup case. Inside the case there's a bottle of bright red nail polish. This isn't just any old nail polish; it's nail polish made with snake venom—rattlesnake venom, to be precise. Having painted her nails, the Warden proceeds to slap the hapless Mr. Sir right across the face, breaking the skin. He falls to the floor, writhing in pain. The Warden's unique brand of nail polish is toxic when wet, but although Mr. Sir will survive, it's still a pretty unpleasant conflict situation, nonetheless.