"Southbound" is a song about cruising on the Interstate 5 highway, which will basically take you from Canada to Mexico while passing through Washington, Oregon, and California. If you start in Washington, where MxPx is from, you can spend most of the day driving before you pass the San Onofre Power Plant, also known as the "nuclear tits," which is/are referenced in the Descendents song "Kids (on Coffee)."
What songs do you crank up while taking a cruise?
"Southbound" by MxPx
"Kids" by Descendents