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.
(..) but it just feels so right. Orson is just the most warm, wonderful, generous man. Oh, generous. That means he's good in the sack. Actually, uh, no. We haven't had sex yet. We're waiting until we get married. Oh, my God. You're serious? (..)2006 TvShow: Desperate Housewives Title: Listen to the Rain on the Roof Season: 3 Episode 1