humf uhmf hmuf mhuf umhf muhf hufm uhfm hfum fhum ufhm fuhm hmfu mhfu hfmu fhmu mfhu fmhu umfh mufh ufmh fumh mfuh fmuh
Note: these 'words' (valid or invalid) are all the permutations of the word humf. These words are obtained by scrambling the letters in humf.