Synonyms and related words :
as a joke, devilishly, elfishly, for amusement, for fun, for kicks, for laughs, for sport, impishly, in jest, in joke, in play, in sport, jestingly, jokingly, knavishly, mischievously, playfully, prankishly, puckishly, roguishly, scampishly, sportively, waggishly