Source : Webster's Revised Unabridged Dictionary (1913)

Misbehave \Mis`be*have"\, v. t. & i. [imp. & p. p. {Misbehaved};
   p. pr. & vb. n. {Misbehaving}.]
   To behave ill; to conduct one's self improperly; -- often
   used with a reciprocal pronoun.