Whoever said these guys were a well-regulated militia?

The truck had the Second Amendment printed on the rear window. Guys, I'm sorry, I am a truck guy but I just don't get the whole weird American passion of the gun thing. Something kind of fetishistic about it. What does a depressed Mainer with an automatic rifle--or 17 year old boy with an itchy finger-- have to do with 'well-regulated militia'?