ball-lickin' good

kfc adverts would have you believe that their food is "finger-lickin' good", but many people disagree, and find this particular brand of fried bird entrails to be somewhat unpleasant - hence tarnishing the positivity of the phrase.
thus, "ball-lickin' good" has become the phrase of choice to signify something that really is quite exceptionally good.
logically speaking, this makes more sense: surveys have shown that 97% of men would rather have their balls licked than their fingers.