People up to no good

What does this mean?

“We come to associate night dwellers with people up to no good…”

Hello cooliegirly,

Here is another way of saying this:

We often think that people who live more at night behave badly or do harmful things.

Night dwellers are also called: night owls (I’m one!), nighthawks, nightbirds or night prowlers.

Yes, they could be up to something.