hafts ahfts hfats fhats afhts fahts hatfs ahtfs htafs thafs athfs tahfs hftas fhtas htfas thfas fthas tfhas afths faths atfhs tafhs ftahs tfahs hafst ahfst hfast fhast afhst fahst hasft ahsft hsaft shaft ashft sahft hfsat fhsat hsfat shfat fshat sfhat afsht fasht asfht safht fsaht sfaht hatsf ahtsf htasf thasf athsf tahsf hastf ahstf hsatf shatf ashtf sahtf htsaf thsaf hstaf shtaf tshaf sthaf atshf tashf asthf sathf tsahf stahf hftsa fhtsa htfsa thfsa fthsa tfhsa hfsta fhsta hsfta shfta fshta sfhta htsfa thsfa hstfa shtfa tshfa sthfa ftsha tfsha fstha sftha tsfha stfha aftsh fatsh atfsh tafsh ftash tfash afsth fasth asfth safth fsath sfath atsfh tasfh astfh satfh tsafh stafh ftsah tfsah fstah sftah tsfah stfah
Note: these 'words' (valid or invalid) are all the permutations of the word hafts. These words are obtained by scrambling the letters in hafts.