Okay, begin witty caption contest for this rugged DIY speaker system...now! "You can play your explosively good music?" "For use only when you really need to blast your tunes?" "Only plays songs that charted number one with a bullet?" "Solder up this stereo, soldier?"
Even if you're not someone known for shopping your local army surplus store or own anything else ammo-related, this fun and effective project might be worth trying, just to learn about the basics of bulding a powered speaker/amplification system into an existing structure. If olive drab just doesn't do it for you, apply the parts list/wiring technique to anything you can think of!