queb uqeb qeub equb ueqb euqb qube uqbe qbue bque ubqe buqe qebu eqbu qbeu bqeu ebqu bequ uebq eubq ubeq bueq ebuq beuq
Note: these 'words' (valid or invalid) are all the permutations of the word queb. These words are obtained by scrambling the letters in queb.