In your bag

To do something with confidence, sauce, skill, flair, and excellence.

Related to: “Getting your bag” meaning getting your money. “In your bag” is related because it means you’re in your element doing something with the skill and swag of a pro. It means you’re in your element.

Slang history: Related to the 50s slang to have something “in the bag”, which meant it already accomplished, or so assured with confidence, it was as good as done.

You argued that man DOWN! You were in your BAG! He was not ready.