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.
(..) she discarded you like last night's chutney? Yes. Sometimes you've got to take one for the team. Sack up, dude. Fine. Here I go, taking one for the team... in the sack. - Hey, Leslie. - Hi, guys. (..)2008 TvShow: The Big Bang Theory Title: The Bat Jar Conjecture Season: 1 Episode 13