(n.) Irresponsibility; levity; trifling; whimsy\; acts or habits of trifling; unbecoming levity of disposition.

amusement asininity battiness big deal brainlessness buffoonery clownishness crackpottedness crankiness craziness daffiness dallying desipience eccentricity emptiness fatuity fatuousness flightiness flimsiness flippancy flirting folly foolery foolheadedness foolishness frivolousness fun futility game giddiness glee gleefulness goofiness high glee hilariousness hilarity idiocy idleness imbecility inanity ineptitude insanity jest jocularity jocundity jolliness jollity joviality joy joyfulness joyousness laughter levity lightness lunacy madness merriment merriness mindlessness mirth mirthfulness niaiserie nugacity nuttiness play playfulness prankishness pranksomeness queerness roguishness sappiness screwiness senselessness shallowness silliness slenderness slightness sport sportiveness stupidity superficiality thoughtlessness toying trickery trickiness trifling triflingness triteness triviality trivialness vacuity vanity vapidity volatility wackiness waggery waggishness weirdness witlessness zaniness zanyism