adj. 25B6; adjective
a mischievous child : NAUGHTY, badly behaved, misbehaving, disobedient, troublesome, full of mischief; rascally, roguish.
a mischievous smile : PLAYFUL, teasing, wicked, impish, roguish, arch.
a mischievous allegation : MALICIOUS, malevolent, spiteful, venomous, poisonous, evil-intentioned, evil, baleful, vindictive, vengeful, vitriolic, rancorous, malign, malignant, pernicious, mean, nasty, harmful, hurtful, cruel, unkind; informal bitchy, catty; poetic/literary malefic, maleficent.
well behaved.