sifts isfts sfits fsits ifsts fists sitfs istfs stifs tsifs itsfs tisfs sftis fstis stfis tsfis ftsis tfsis iftss fitss itfss tifss ftiss tfiss sifst isfst sfist fsist ifsst fisst sisft issft ssift ssift issft sisft sfsit fssit ssfit ssfit fssit sfsit ifsst fisst isfst sifst fsist sfist sitsf istsf stisf tsisf itssf tissf sistf isstf ssitf ssitf isstf sistf stsif tssif sstif sstif tssif stsif itssf tissf istsf sitsf tsisf stisf sftsi fstsi stfsi tsfsi ftssi tfssi sfsti fssti ssfti ssfti fssti sfsti stsfi tssfi sstfi sstfi tssfi stsfi ftssi tfssi fstsi sftsi tsfsi stfsi iftss fitss itfss tifss ftiss tfiss ifsts fists isfts sifts fsits sfits itsfs tisfs istfs sitfs tsifs stifs ftsis tfsis fstis sftis tsfis stfis
Note: these 'words' (valid or invalid) are all the permutations of the word sifts. These words are obtained by scrambling the letters in sifts.