How did Grandpa’s bragging get Billy into trouble with the Pritchard boys?

Billy to go to the mill to get some corn ground. Upon Billy's arrival at Grandpa's store, he runs into Rubin and Rainie Pritchard. They are boys with a bad reputation and no one likes them. They bet Billy two dollars that his hounds cannot catch a coon that has been running around in their part of the country for years. They call him the ghost coon. They also think that their dog is better than Billy's and that the reputation of Billy's dogs is just a bunch of lies. Grandpa encourages Billy (by bragging) to agree to the bet and he does. He gives Billy the money to hold on to. The boys agree to meet tomorrow night up by the Pritchards' part of the country. Grandpa tells Billy how badly he wants him to catch that coon and Billy knows he will. Billy thinks his Grandpa is the best grandfather a boy could have.