on $*:text:/^((?!#charity).)*$/i:#matrixis: {
  var %starttime = $ctime(18/12/2017 00:00:00)
  var %endtime = $ctime(29/12/2017 23:59:59)
  if ($ctime >= %starttime) && ($ctime <= %endtime) {
    if ($msgtags(bits).key) {
      msg # Don't forget to use #charity in all bit messages from 18th - 29th December
    }
  }
}