kexs ekxs kxes xkes exks xeks kesx eksx ksex skex eskx sekx kxse xkse ksxe skxe xske sxke exsk xesk esxk sexk xsek sxek
Note: these 'words' (valid or invalid) are all the permutations of the word kexs. These words are obtained by scrambling the letters in kexs.