sacfu ascfu scafu csafu acsfu casfu safcu asfcu sfacu fsacu afscu fascu scfau csfau sfcau fscau cfsau fcsau acfsu cafsu afcsu facsu cfasu fcasu sacuf ascuf scauf csauf acsuf casuf saucf asucf suacf usacf auscf uascf scuaf csuaf sucaf uscaf cusaf ucsaf acusf causf aucsf uacsf cuasf ucasf safuc asfuc sfauc fsauc afsuc fasuc saufc asufc suafc usafc ausfc uasfc sfuac fsuac sufac usfac fusac ufsac afusc fausc aufsc uafsc fuasc ufasc scfua csfua sfcua fscua cfsua fcsua scufa csufa sucfa uscfa cusfa ucsfa sfuca fsuca sufca usfca fusca ufsca cfusa fcusa cufsa ucfsa fucsa ufcsa acfus cafus afcus facus cfaus fcaus acufs caufs aucfs uacfs cuafs ucafs afucs faucs aufcs uafcs fuacs ufacs cfuas fcuas cufas ucfas fucas ufcas
Note: these 'words' (valid or invalid) are all the permutations of the word sacfu. These words are obtained by scrambling the letters in sacfu.