perx eprx prex rpex erpx repx pexr epxr pxer xper expr xepr prxe rpxe pxre xpre rxpe xrpe erxp rexp exrp xerp rxep xrep
Note: these 'words' (valid or invalid) are all the permutations of the word perx. These words are obtained by scrambling the letters in perx.