This is Eclectic Method's 'Boom Bang', a song made from a kid making weapon sound effects, with clips from war movies acting as the song's music video. I'll be honest, when it first started I wasn't that into it, but by the time I was thirty seconds deep I had already made it my ringtone and was searching online how to hack my doorbell.
Keep going for the video, and "Don't worry the kid doing the sound effects didn't watch Apocalypse Now, didn't really say 'I love the smell of Napalm in the morning' and doesn't really know what these sounds are , except maybe the helicopter." Well that's a relief.
Thanks to Clint, who agrees somebody needs to make a 'Pew Pew Pew' song if they haven't already.