1.) A word used to express absolutely any form of emotion, be it extreme or minor. Sadness, anger, confusion, joy, no emotion, or even arousal..
2.) Symbolizing acknowledgement; confirmation..
"Yurg!! I forgot to turn in my paper!"
"What the yurg are you talking about."
"Holy yurg, I have a massive erection."
"Yurg, I got my chores done."
"I don't know what else to say, so I'll say Yurg."