up to no good
1
about to do something bad or evil
The exact origin of the idiom "up to no good" is unclear, as it has been a part of the English language for a significant period of time. The phrase is derived from the combination of "up to," meaning engaged in or involved in, and "no good," which refers to actions or intentions that are negative, dishonest, or harmful. It is commonly used in informal conversations, storytelling, or when expressing skepticism or distrust towards someone.
- I saw those kids hanging out near the abandoned building again; they must be up to no good.
- Whenever he gets that secretive look on his face, you know he's up to no good.
- The security guard noticed a group of people loitering around the parking lot late at night and suspected they were up to no good.
- The teacher caught the students passing notes during the exam and knew they were up to no good.
- She had a feeling that her coworker's sudden interest in the company's financial records meant he was up to no good.