No idea - please provide the full context.

It means "you did well watching out for something", sometimes to protect another person. "You accidentally mispelled our client's name on that letter, but I fixed it." "Good lookin' out." "I noticed pickpockets at this station, so I packed our wallets in our suitcase." "Good lookin' out."

It sounds like a dialect. It's not standard English, and I have no idea what it means. If you post the full sentence we might be able to figure it out.