Got a flat on a ride today. Pulled over, sat on a side street and did the usual routine, pop off the rear wheel, pull out the tube, check the tire for glass, wire, etc. I then popped in a CO2 cartridge, twisted the handle of the "Inflater-majig" to puncture it, inflated the new tube a little, popped it in the tire then seated the bead, fully inflated the tube. Still sitting on the road I grabbed the old tube and stuck it my back jersey pocket, stuck my tire levers in the seat bag. I then unscrewed the handle of the "Inflater-majig" which was holding the CO2 cartridge in place because it immediately shot off like a rocket striking me right in the nuts. Clutching my bruised niblets I fell over onto my side whimpering like a little school girl. Never had THAT happen before...I guess now I've got to get a little helmet for my little helmet.