Untitled

function crazy(normal) {

  var normalArray = normal.split("");

  for (var i = 0; i < 8; i++) {

    var letterIndex = Math.floor(Math.random() * normal.length);

    normalArray[letterIndex] = normalArray[letterIndex].toUpperCase();

  }

  return normalArray.join('');

}

document.write(crazy('oh my god'));