Something

#!/usr/bin/perl -w

use strict;
use vars qw($VERSION %IRSSI);

# This file is partially based on rainbow.pl
$VERSION = "1";
%IRSSI = (
authors => 'Wilmer van der Gaast',
contact => 'lintux@lintux.cx,
name => 'Fake-Ignore',
license => 'GNU GPLv2 or later',
);

use Irssi;
use Irssi::Irc;

sub fignore {
  my ($text, $server, $dest) = @_;

  if (!$server || !$server->{connected}) {
    Irssi::print("Not connected to server");
    return;
  }

  return unless $dest;
  if ($dest->{type} eq "CHANNEL" || $dest->{type} eq "QUERY") {
    $text = `date +%H:%M:%S` . ' Ignoring ALL from ' . $text;
    $text =~ s/[\n\r }+/ /gs;
    $dest->command("/msg " . $dest->{name} . " " . $text );
  }
}

Irssi::command_bind( "fignore", "fignore" );