For me this popped in wordament (adventure). I'm not sure if you can also unlock it in other game modes, but I'm pretty sure jumble doesn't work. You can use your keyboard to type words, which is much faster then using the mouse. Find a few 3 or 4 letter words but don't type them yet. Then once you are good to go, start typing and making the words. Not that hard.
Might be a coincidence but it popped for me upon completing the puzzle.