busq ubsq bsuq sbuq usbq subq buqs ubqs bqus qbus uqbs qubs bsqu sbqu bqsu qbsu sqbu qsbu usqb suqb uqsb qusb squb qsub
Note: these 'words' (valid or invalid) are all the permutations of the word busq. These words are obtained by scrambling the letters in busq.