You have to be on your toes at my house. You never know when someone will jump out and yell trying to scare you or shoot you in the face with the wrapper from a straw. We also have some NERF guns, and the only way I get any warning that I am about to get shot is when my daughter has to get me to cock the thing for her so she can then go hide somewhere and shoot me as I walk by.
Simon, a geeky DIY sort from New Zealand, has taken it upon himself to build his own NERF pistol and the thing is really cool. He used some L33t DIY skillz along with some 32mm ID PVC pipe, aluminum extrusion tubing, and a spring from a rifle to actually shoot the Nerf bullet out.
The handle of the gun is carved wood with a plastic overlay and it has some other parts. I am wondering where the trigger mechanism came from, it seems like it would be one of the harder components to make to me. The finished product looks like some sort of Luger animal tranquilizer shooter.