str = str.replace(/([aeiou])([^aeiouy\W\d])\2(?=y\b)/gmi, "$2$1$1");
This one horrifying, disgustingly long line of JavaScript code will “bnuuy-ify” every eligible word in the string “str”. “Bunny” of course becomes “Bnuuy”, “doggy” becomes “dgooy”, “kitty” becomes “ktiiy”, etc.
You might be wondering why I did this. I might also be wondering that. Maybe because it’s fnuuy?