firks ifrks friks rfiks irfks rifks fikrs ifkrs fkirs kfirs ikfrs kifrs frkis rfkis fkris kfris rkfis krfis irkfs rikfs ikrfs kirfs rkifs krifs firsk ifrsk frisk rfisk irfsk rifsk fisrk ifsrk fsirk sfirk isfrk sifrk frsik rfsik fsrik sfrik rsfik srfik irsfk risfk isrfk sirfk rsifk srifk fiksr ifksr fkisr kfisr ikfsr kifsr fiskr ifskr fsikr sfikr isfkr sifkr fksir kfsir fskir sfkir ksfir skfir iksfr kisfr iskfr sikfr ksifr skifr frksi rfksi fkrsi kfrsi rkfsi krfsi frski rfski fsrki sfrki rsfki srfki fksri kfsri fskri sfkri ksfri skfri rksfi krsfi rskfi srkfi ksrfi skrfi irksf riksf ikrsf kirsf rkisf krisf irskf riskf isrkf sirkf rsikf srikf iksrf kisrf iskrf sikrf ksirf skirf rksif krsif rskif srkif ksrif skrif
Note: these 'words' (valid or invalid) are all the permutations of the word firks. These words are obtained by scrambling the letters in firks.