on *:text:!tkb*:#: {  
  if ($nick isop $chan) { 
    if ($2 !ison #) halt
    elseif (!$2) notice $nick You didn't specify who to ban
    else {
      /ban -ku $+ $calc($iif(!$3,3,$3) * 60) $chan $2 2 You will be unbanned in $iif(!$3,3,$3) minutes 
    }
  } 
}