She has a reputation for being 'good/great in the sack'. [=for being a good sexual partner]
He's ready to 'jump/climb in the sack' [=have sex] with any woman who'll have him.
The company 'gave him the sack' [=fired him] for improper conduct.
(..) Say Prince Theon. I've yielded Winterfell to Prince Theon. You all know me. Aye, we know you for a steaming sack of shit. Farlen, you be silent. Listen to your little Lord, Farlen. He has more sense than you do. (..)2012 TvShow: Game of Thrones Title: The Old Gods and the New Season: 2 Episode 6