Alright. Its late, and I am bored. Lets say one has a text string, and ones friend is sitting on the other side of the table. One would like them to be able to read this string, but one does not want to turn their computer around, because that would be too much of a hassle. One one would smart to quickly write a program in ones favorite language, Powershell, to flip all of the characters for them. One is not too concerned about efficiency here, because one is watching 'The Transporter'. Actually, it just got to the good part. So one is really hammering out pshell to get this stupid thing to work.

raw

function Flip-Text
{
    [CmdLetBinding()]
    param
    (
        [Parameter(Mandatory=$true, ValueFromPipeline=$true, Position=0)][String]$text
    )
    process
    {
        $rightSide='abcdefghijklmnopqrstuvwxyz0123456789&_<>?!()[]{}'
        $upsidedown='ɐqɔpǝɟƃɥıɾʞʃɯuodbɹsʇnʌʍxʎz012Ɛᔭ59Ɫ86⅋‾><¿¡)(][}{'
        $output = ""
        for($i = $text.Length -1; $i -ge 0; $i--)
        {
            $c = $text[$i]
            $indR = $rightSide.IndexOf($c)
            $indU = $upsidedown.IndexOf($c)

            if($indR -gt 0)
            {
                $output += $upsidedown[$indR]
            }
            elseif($indU -gt 0)
            {
                $output += $rightSide[$indU]
            }
            else{
                $output += $c
            }
        }

        return $output
    }
}

So there was the program. All it really does, it maps right side up characters to their inverse. In the spirit of the rest of this site, here is an ugly one liner which does the same thing. Pretty much it's just the first answer all mushed together, but it sure looks cool.

raw

function Flip-Text2
{
    [CmdLetBinding()]
    param
    (
        [Parameter(Mandatory=$true, ValueFromPipeline=$true, Position=0)][String]$text
    )
    process
    {
        ($text[($text.Length-1)..0]|%{'ɐqɔpǝɟƃɥıɾʞʃɯuodbɹsʇnʌʍxʎz012Ɛᔭ59Ɫ86⅋‾><¿¡)(][}{ '[("$(97..122|%{[char]$_})$(0..9)&_<>?!()[]{}"-replace' ','').IndexOf($_)]})-join''
    }
}