Okay, I know I've probably posted this in a comment helping someone else on here pertaining to some rainbow text snippet. I made this around a year ago? Maybe? I don't really remember. It's been a while. However, I felt the need to just post it as a snippet myself that way people can find it. It includes right click options on mIRC to enable or disable each feature.

Features include Rainbow text only, reversed text only, or both options at the same time. :D

Note: You do NOT have to disable previous options to enable a new one. It automatically disables the previous option for you. :) However, you do have to disable the current option to use default text.

menu channel,status,nicklist {
  Default Output
  .Rainbow
  ..On: set %rbow true | set %reverse false | set %rainverse false | echo 9 Rainbow text is now enabled
  ..Off: set %rbow false | echo 4 Rainbow text is now disabled
  .Reverse
  ..On: set %reverse true | set %rbow false | set %rainverse false | echo 9 Reverse text is now enabled
  ..Off: set %reverse false | echo 4 Reverse text is now disabled
  .Both
  ..On: set %rainverse true | set %rbow false | set %reverse false | echo 9 Both options are now enabled
  ..Off: set %rainverse false | echo 4 Both options are now disabled
}
on *:INPUT:#:{
  if ($left($1,1) != /) {
        msg $active $iif(%rbow == true,$rainbow($1-),$iif(%reverse == true,$rev($1-),$iif(%rainverse == true,$rainbow($rev($1-)),$1-)))
haltdef
  }
}

alias -l nextcolor { 
  if ($$1 == 04) return 07
  elseif ($$1 == 07) return 08
  elseif ($$1 == 08) return 09
  elseif ($$1 == 09) return 11
  elseif ($$1 == 11) return 12
  elseif ($$1 == 12) return 02
  elseif ($$1 == 02) return 06
  elseif ($$1 == 06) return 13
  elseif ($$1 == 13) return 04
}
alias -l rainbow {
  var %pos = 1, %color = 04, %result = $chr(3)
  while (%pos <= $len($1-)) {
    %result = %result $+ %color $+ $mid($1-,%pos,1) $+ $chr(3)
    inc %pos
    %color = $nextcolor(%color)
  }
  if ($isid) return %result
  else say %result
}

alias -l rev {
  var %len = $len($1-)
  var %return = $null
  while (%len > 0) {
    var %return = %return $+ $mid($1-,%len,1) $+ $chr(32)
    dec %len
  }
  return %return
}