Cause trouble, as in Don't listen to her gossip—she's just trying to make mischief. This idiom was first recorded in 1884, but the related noun mischief-maker, a person who causes trouble especially by tale-bearing, dates from about 1700.
Examples from the Web for make mischief
"I alway b'rieve some make-mischief tell Masser dat time;" returned the negro sulkily, though not without doubt.The Water-Witch or, The Skimmer of the Seas
James Fenimore Cooper