You may want to drink one, but you don't want to be a bag of juice.
Quite a few things probably spring to mind when you think about the meaning of Saftsack or "juice sack." Your mind might conjure up a carton of juice or a fruity cocktail or something altogether more unsavory. Well, with "unsavory" you'd be on the right track. In German, Saftsack is an insult: "You Saftsack! Get off the road!" is not an uncommon phrase shouted out by angry drivers. It can also refer to a cowardly person with no backbone.