da chain?

"dat's cool." billy says

"it's off the chain." i add.

"dat's cooool!" billy repeats.

"that's cool, that's off the chain." i say.

"chain?"

"yeah! off the chain!"

"WHAAA? da chain? wha chain?" he says as he looks at me quite puzzled.

"off. the. chain. it means it's cool. it's off the chain."

"oh, off da chain!?"

"yeah! off the chain!!!"

"noooo. no off a chain!" he shouts angrily.

i'd be angry too if someone kept pestering me about street lingo.