up to no good
Meaning
Behaving suspiciously or doing something wrong or mischievous.
Origin
From the older sense of “up to” meaning “engaged in/occupied with” (seen since the 1700s). So “up to no good” literally means engaged in something not good, i.e., mischief or wrongdoing.
Notes
Common in conversation to suggest suspicion or mischief, from minor pranks to serious wrongdoing. Often implies you don’t know exactly what, just that it seems bad.
Examples
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The kids were being unusually quiet, so I knew they were up to no good.
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I saw him lurking near the back door, and it looked like he was up to no good.
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Whenever that group shows up after midnight, they’re usually up to no good.
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Don’t trust that “free prize” email—it’s definitely up to no good.
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She gave me that guilty smile, like she was up to no good again.
Grammar & Usage Notes
Fixed pattern: “be up to no good” (am/is/are/was/were). Can take time phrases (“again,” “as usual”) but “no good” stays unchanged. Not normally used as a noun phrase.
Synonyms
- up to something
- plotting something
- up to mischief
- up to no good tricks
Antonyms
- on the level
- well-behaved
- up to something good