Ok, obviously this is not an original idea because there's a picture of it right below....however, it doesn't make it any less awesome. If you grew up in the mid-west and had a father who was a hunter / fisher type guy, you probably owned a Daisy Red Ryder BB gun. Yep, if you've seen the cult classic movie A Christmas Story, it's the same BB gun that Ralphy wanted ("You'll shoot your eye out"). How does this relate to bicycles?
Just take a look along his front fork....a bicycle mounted gun scabbard with a BB gun. While technically it's not the Red Ryder (it's an even smaller version) I think you see the point. And not that I'm recommending this....but here's this guy in action with it!
Also for the record I don't know this guy. I found an article with these pics over at Velodirt.com. This was a fairly epic ride that some of those guys did out in the Hart Mountain Antelope Refuge. You can read the full story over there!