I thought that instead of breathing fire through your mouth, you might try to sneeze it out. Since there is no category (that I could find) for fire-breathing, I decided to put the idea here.

The fuel would have to be something that would irritate the mucus membranes but would also be non-toxic and flammable.

You could also use this as a way of atomizing fuel in a car, although you would have to use several passangers to make the fuel supply consistant. It might be best for a large bus or van.

It would not be practical or healthy for the passengers, but would probably be better than a flattulence-powered vehicle (excluding the use of bean burritos).