Answer: "No yelling on the bus!"
When Billy's third grade class went on a field trip, they had a bus driver (played by Chris Farley) who seemed to have an anger management problem. On the way to the field trip, he muttered to himself a lot and his face turned bright red. After the kids boarded the bus for the return trip, the driver got on behind them and yelled, "No yelling on the bus!" The driver, along with Billy's adult friends, also ate all of the kids' lunches. It was also on this field trip that Billy's friend Ernie peed his pants, leading Billy to pretend he peed his pants too, so the kids would think Ernie was cool for doing what Billy did.