someone who is mischievous likes to have fun, especially by playing tricks on people or doing things to annoy or embarrass them:
Their sons are noisy and mischievous.
mischievous smile/look etc
Gabby looked at him with a mischievous grin.
There was a mischievous gleam in her eyes.
causing trouble or quarrels deliberately:
a mischievous remark
He grinned mischievously.
—mischievousness noun [uncountable]