A catalytic converter is a piece of metal core which heats up to an extreme temperature in order to help in burning the polutants that may have escaped combustion in the actual combustion chamber. I have bump-started many cars with cats, and this is a theory that someone came up with to sound smart... and with little foundation in reality. The amount of unburnt gas in the cat would have to be pretty high, or over a prolonged period of time to damage it. Bump em if they got the right amnount of pedals - if not, the'y're not really cars, so who cares.