foolish or silly behavior; tomfoolishness.

a silly act, matter, or thing.

noun

absurdity , antics , bunk , carrying-on , clowning , craziness , folly , foolery , fooling around , foolishness , fun , funny business , giddiness , high jinks , horseplay , insanity , irresponsibility , joking , kidding around , ludicrousness , lunacy , madness , ridiculousness , senselessness , shenanigans * , silliness , idiocy , imbecility , nonsense , preposterousness , zaniness , devilry , deviltry , diablerie , impishness , mischievousness , prankishness , rascality , roguery , roguishness , balderdash , blather , bunkum , claptrap , drivel , garbage , piffle , poppycock , rigmarole , rubbish , trash , twaddle , (colloq.) folly , caper , frolic , malarkey , monkey-tricks , mummery , prank , trifling