nurr unrr nrur rnur urnr runr nurr unrr nrur rnur urnr runr nrru rnru nrru rnru rrnu rrnu urrn rurn urrn rurn rrun rrun
Note: these 'words' (valid or invalid) are all the permutations of the word nurr. These words are obtained by scrambling the letters in nurr.