This sums it up perfectly
Unusual duels
In 1808, two Frenchmen are said to have fought in balloons over Paris, each attempting to shoot and puncture the other's balloon; one duelist is said to have been shot down and killed with his second.[7]
Thirty-five years later (1843), two men are said to have fought a duel by means of throwing billiard balls at each other.[7]
Some participants in a duel, given the choice of weapons, are said to have deliberately chosen ridiculous weapons such as howitzers, sledgehammers, or forkfuls of pig dung, in order to show their disdain for duelling.[7]
It is said (though not confirmed) that Otto von Bismarck challenged Rudolf Virchow to a duel. As the challenged party had the choice of weapons, Virchow chose two sausages, one of which had been inoculated with cholera. Bismarck is said to have called off the duel at once.[8]
http://en.wikipedia.org/wiki/Duels
Also, I'd say spitting at dawn!