Lyric discussion by Burn the Witch 

Cover art for Big Trucks lyrics by Pedro the Lion

To me, this song is a lesson in patience, the son, who, because he is young "jumps the gun" unlike the father.

Obviously the son wants his father to teach another person a lesson for insulting him (maybe because he is a Christian, who knows?) but the father uses the metaphor of being stuck behind a truck on the road. Sure, you might be in a rush, but the driver can't go as fast as you. You can't just lose your temper over something so trivial.