Something you call someone when you have no idea what else to call them. Generally these people tend to be similar to mother fucking, ass master, penis breathed, dickholes. The difference is that to call them that would not offend them. Hence the term "dursh" arived insult the uninsultable.
Combination of a Douche and Fred Durst. And since Fred Durst is the ultimate Douche, then calling someone a Dursh is basically calling the biggestDouche Bag ever.
"check outthat guy in the Sweater-Vest, He's such a Dursh!"
, "My ATV got so much air on that jump" - "Whatever Dursh!"