The original origin of the term comes from the novel series "Malazan Book of the Fallen" by Steven Erikson. Within the story, one of the sappers (or combat engineer) uses a 'cusser', which is an extremely explosive alchemical clay ball to save his squad and kill an enemy demon by running up to it and throwing it at the ground.
The act is only half of the process. One must be excited, or jubilant, possibly uttering a celebratory cry of triumph.
-"The guy suddenly ran at me and hedged us both to smitherines"
-"What the crap, who's the hedger?"
-"Thats it, I'm hedging!"