zzyx zzyx zyzx yzzx zyzx yzzx zzxy zzxy zxzy xzzy zxzy xzzy zyxz yzxz zxyz xzyz yxzz xyzz zyxz yzxz zxyz xzyz yxzz xyzz
Note: these 'words' (valid or invalid) are all the permutations of the word zzyx. These words are obtained by scrambling the letters in zzyx.