As with 'awesome sauce', this is an exclamation or reserved sign of approval. The difference in this case being that the exclamation comes in the form of both complimenting and envying the guy wearing a Green Jacket.
Steve: So'd anything happen with that chick you met at the bar last weekend?
Dave: Not this time, brother.
Steve: No--damn dude, you guys hit it off at first, what happened this time?
Dave: The first time, she was feelin' the 'Green Jacket Sauce.' This tme, I wasn't wearing it.