LOL, now that's funny as well. Just think about all of the various cases out there that we've never even heard about.
Back on MARLIN's story for a moment-- the pour spout on a Diesel pump is intentionally bigger so it can't fit into a normal car's Unleaded filler neck pipe (thereby preventing Diesel going into an Unleaded car). However, the smaller Unleaded pour spout will easily fit inside the bigger filler neck pipe of a Diesel vehicle (as was the case with MARLIN's wifey). I guess mankind can only help prevent gender mistakes to a certain degree.
Maybe the fuel industry should change the pour spout and filler neck pipe for Diesel to an "Hour Glass" (inverted diamond shape like on a Black Widow spider). Basically, some other distinct shape that a common round pipe won't match up fitting. Then the round Unleaded pour spout won't fit into the Hour Glass shaped filler neck of a Diesel vehicle; and vice versa, the Hour Glass shaped Diesel pour spout still won't fit into a round shaped filler neck of a Unleaded vehicle (as is currently the case). Brilliant!!!
As for your idea, I doubt it would work. Diesel engines run for a LONG LONG time, so you would have to wait 10-20 yrs before you could swap out all the pump nozzles. How about all you regular gas users swap your filler pipes to the hourglass shape.
