All 5 Uses

mischievous
in
Matched, by Ally Condie
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Bram grins mischievously at me, still wearing his sleep-clothes.†
p. 23.9 *

mischievously = in a manner that playfully causes minor trouble
Everyone turns to stare at me and he grins mischievously.†
p. 41.9
Grandfather's eyes gleam mischievously.†
p. 62.7
"I'm an old hypocrite, too," he says, his eyes mischievous again.†
p. 82.2
He's no longer smiling but his eyes are mischievous.†
p. 240.1

Definitions:

(1) (mischievous)
playfully causing minor trouble; or describing the smile of someone doing so

Much less commonly, mischievous can reference real harm without any sense of fun. But in modern writing, that usage has largely shifted to other words like malicious, destructive, or damaging.
(2) (meaning too rare to warrant focus)
In law, mischievous references a property crime such as vandalism or graffiti. Very rarely, the word can reference someone or something causing serious damage.

In archaic literature mischievous often refers to bad behavior without any connotation of playfulness or of the harm being minor.