Go south = to loose value or quality ; (situation) to become very bad.
(بی ارزش شدن ؛ بدتر شدن)
Have a way with somebody/ something = have a special ability to do something.
(توانایی خاصی برای انجام کاری داشتن)
Keep something under wraps = keep it secret.
(محرمانه نگه داشتن)