n. 25B6; noun
the boys are always getting up to mischief : NAUGHTINESS, bad behaviour, misbehaviour, mischievousness, misconduct, disobedience; pranks, tricks, larks, capers, nonsense, devilry, funny business; informal monkey business, shenanigans, hanky-panky; Brit. informal monkey tricks, carryings-on, jiggery-pokery.
the mischief in her eyes : IMPISHNESS, roguishness, devilment.
(informal) you'll do yourself a mischief : HARM, hurt, injury, damage.