This should work, don't forget to change the channel you want it to work in in the first line of the on join event. You can use multiple channels by seperating them with a comma. Also don't forget to change the words it will check for in the %x variable.

Code:
on *:join:#channel: {
  ; Store a list of words to look for.
  var %x = jerk punk loser dork
  ; If their ident is in the above list, then:
  if ($gettok($remove($address($nick,0),*!),1,64) isin %x) {
    ; Set a wildcard ban on that ident in the form of *word*
    mode $chan +b $+(*!*,$ifmatch,*@*)
    ; Kick them out..
    kick $chan $nick Please change your ident to rejoin.
  }
}