Phrasal Verb: Sit on

Meaning: Be on a committee

Example: She's SAT ON the finance committee from the beginning.

Meaning: To handle somebody firmly who behaves impertinently, conceitedly

Example: If his girlfriend finds out, she'll get mad and SIT ON him.

Meaning: Hold information back or keep it secret

Example: The government have been SITTING ON the report because it was so critical.