Complex sentence: The boys tell their parents they are going to attend the National Grammar Rodeo in Canada, but secretly take the rented car for a road trip to the World's Fair in Knoxville, Tennessee.
Split into simpler sentences: The boys tell their parents they are going to attend the National Grammar Rodeo in Canada, but secretly take the rented car for a road trip. During their trip, they decide to go to the World's Fair in Knoxville, Tennessee.