Usage: KICK *|<channel> <user> [<comment>]
  Kicks specified user off a given channel.  Only channel operators
  are privileged to use this command.  Channel operator privileges
  can be given to other users of channel using:
    MODE <channel> +o <user>
  and taken away with:
    MODE <channel> -o <user>
  KICK * <user> is just like the first usage but it always specifies
  the current channel.  So 
    KICK * idiot
  will kick 'idiot' off your current active channel.

  KICK can be very effective if used in a combination with
    MODE #channel +i
  and possibly
    MODE #channel +b.
  First line of defense should be IGNORE and KICK then then the
  channel can be made invite only, and if all else fails a person
  can be banned from the channel.
 
  The <comment> is to supply some reason for the kick to the user
  affected as well as to other people on your channel.

IMPORTANT NOTE:
  Be careful with your use of KICK and MODE #channel -o
  as they can throw the network permanently out of sync.  This
  generally occurs when two people are bickering about channel op
  status and de-op each other.  This generates 'Fake MODE' notices
  which are an indication that something is wrong.  The best way
  to avoid this is to not use ON and MODE together.