Awesome, hot fire, great, sick, etc.
"Whoa the Giants won the Superbowl that's so dopecity."
The "city" term can be added to the end of several words to add extra emotion/stress something.
Guy 1- "Hey man did you see that guy wearing those pink booty shorts?"
Guy 2- "Yeah bro he was madd gaycity."
At the beginning of a beer pong game whilst teammates are filling up the cups, they accidentally pour into the same cup
Tim: "Oh man we just totally fiddled!"
Mark" "Yeah we did man! Big Fiddling Fiddler McFiddlestein!"