Source : Webster's Revised Unabridged Dictionary (1913)

Fool \Fool\, v. i. [imp. & p. p. {Fooled}; p. pr. & vb. n.
   {Fooling}.]
   To play the fool; to trifle; to toy; to spend time in idle
   sport or mirth.

Source : WordNet®

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