up to no good

up to no good

Engaging in malicious or nefarious behavior. I'm worried that my daughter's boyfriend is up to no good—he always seems to be involved in some bizarre scheme. What are you boys whispering about? You're up to no good, aren't you?
See also: good, no, up
Farlex Dictionary of Idioms.

up to no good

Fig. doing something bad. I could tell from the look on Tom's face that he was up to no good. There are three boys in the front yard. I don't know what they are doing, but I think they are up to no good.
See also: good, no, up
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

up to no good

doing or intending to do something wrong. informal
1997 Iain Sinclair Lights Out for the Territory ‘Here we are then,’ he said, ‘two boyos from the valleys up to no good in the big, wicked city.’
See also: good, no, up
Farlex Partner Idioms Dictionary

up to no ˈgood

(informal) doing or planning something wrong or dishonest: He doesn’t work but he seems to have lots of money. I’m sure he’s up to no good. Where have those children gone? They’re probably up to no good.
See also: good, no, up
Farlex Partner Idioms Dictionary
See also:
  • vice
  • vice ring
  • back alley
  • make life difficult
  • make life difficult (for one)
  • make somebody's life a misery
  • misery
  • make (one's) life a misery
  • make life a misery (for one)
  • keep your friends close and your enemies closer