My almost-ten-year-old son helped me with this one!
From the back cover:
Clearly, any field trip involving manure is not right for a bunch of fourteen-year-olds. But manure wasn't even the worst part of the stupid field trip. The worst part was that the farmer grows pigs. And pigs are also called hogs. And there's this poor guy in our class called Dan Hogg who everybody hated.