frivolity

frivolity (http://definr.com/frivolity)

     n 1: the trait of being frivolous; not serious or sensible [syn:
          frivolousness] [ant: seriousness]
     2: something of little value or significance [syn: bagatelle,
         fluff, frippery]
     3: acting like a clown or buffoon [syn: buffoonery, clowning,
         harlequinade, prank]