gtfr tgfr gftr fgtr tfgr ftgr gtrf tgrf grtf rgtf trgf rtgf gfrt fgrt grft rgft frgt rfgt tfrg ftrg trfg rtfg frtg rftg
Note: these 'words' (valid or invalid) are all the permutations of the word gtfr. These words are obtained by scrambling the letters in gtfr.