This is a video demo of the NERF Rival Zeus MXV 1200. It costs $50, runs on C batteries, and can shoot 12 foam balls up to 100-feet per seconds (~68MPH). It is for ages 14 and up and probably should not be pointed directly into your eyeball. Not that that's gonna stop me, but I should probably know better. Whatever happened to running around and shooting ping pong balls out of your mouth? I used to play that as a kid back before I was old enough to be worried about getting cooties.
Keep going for a video of the third next best thing to a paintball gun for a 14-year old.
Thanks to JB, who tried modifying one to shoot chocolate covered marshmallows but now it doesn't work anymore.