The Collaborative International Dictionary of English v.0.48:

Fool \Fool\, v. i. [imp. & p. p. Fooled; p. pr. & vb. n.
   Fooling.]
   To play the fool.
   [1913 Webster]

   2. To waste time in unproductive activity; to spend time in
      idle sport or mirth; to trifle; to toy.

   Syn: fool around.
        [PJC]

              Is this a time for fooling?         --Dryden.
        [1913 Webster]

WordNet (r) 3.0 (2006):

fooling
    adj 1: characterized by a feeling of irresponsibility; "a broken
           back is nothing to be casual about; it is no fooling
           matter" [syn: fooling, casual]

Moby Thesaurus II by Grady Ward, 1.0:

144 Moby Thesaurus words for "fooling":
   badinage, bamboozlement, banter, bantering, befooling, bluffing,
   booing, buffoonery, calculated deception, catcalling, chaff,
   chaffing, circumvention, clownishness, conning, coquetry, dabbling,
   dalliance, dallying, deceiving, deception, deceptiveness,
   defrauding, delusion, delusiveness, derision, derisive, derisory,
   dupery, enmeshment, ensnarement, entanglement, entrapment,
   exchange, fallaciousness, fallacy, falseness, fiddling, fleering,
   flimflam, flimflammery, flippancy, flippant, flirtation,
   fond illusion, foolery, fooling around, give-and-take,
   good-natured banter, grinning, hallucination, harlequinade,
   harmless teasing, hazing, high jinks, hissing, hoodwinking,
   hooting, horseplay, idling, illusion, jape, jeering, jerking off,
   jest, jesting, jive, joke, joking, jollying, josh, joshing,
   kidding, kidding around, leering, levity, loitering,
   messing around, mirage, mockery, mocking, monkeying,
   monkeying around, monkeyshines, outwitting, overreaching, panning,
   persiflage, phantasm, piddling, playing, playing around,
   pleasantry, pottering, puttering, putting on, quizzical, ragging,
   railing, raillery, rallying, razzing, ribbing, ridicule,
   ridiculing, roasting, roughhouse, rowdiness, scoffing,
   self-deception, shenanigans, skylarking, smart, smart-aleckiness,
   smart-alecky, smart-ass, smartness, smattering, smirking, sneering,
   snickering, sniggering, snorting, snow job, song and dance,
   spoofery, spoofing, sport, subterfuge, swindling, taunting,
   teasing, tinkering, tomfoolery, toying, trickiness, tricking,
   trifling, twit, twitting, victimization, vision,
   willful misconception, wishful thinking