Hydrogen bomb

My friend Robert made a home-made hydrogen generator for his car as he commutes between West Virginia and North Carolina every week. It saved him 10 miles a gallon on at least one trip.

He set up a toggle switch to turn the generator off and on and last week forgot to turn it off when he parked the car. When he came back an hour later and started the car there was a little too much hydrogen in the system and he had quite an explosion under the hood.