unpen nupen upnen punen npuen pnuen unepn nuepn uenpn eunpn neupn enupn upenn puenn uepnn eupnn peunn epunn npeun pneun nepun enpun penun epnun unpne nupne upnne punne npune pnune unnpe nunpe unnpe nunpe nnupe nnupe upnne punne unpne nupne pnune npune npnue pnnue nnpue nnpue pnnue npnue unenp nuenp uennp eunnp neunp enunp unnep nunep unnep nunep nnuep nnuep uennp eunnp unenp nuenp enunp neunp nenup ennup nneup nneup ennup nenup upenn puenn uepnn eupnn peunn epunn upnen punen unpen nupen pnuen npuen uenpn eunpn unepn nuepn enupn neupn penun epnun pneun npeun enpun nepun npenu pnenu nepnu enpnu pennu epnnu npneu pnneu nnpeu nnpeu pnneu npneu nenpu ennpu nnepu nnepu ennpu nenpu pennu epnnu pnenu npenu enpnu nepnu
Note: these 'words' (valid or invalid) are all the permutations of the word unpen. These words are obtained by scrambling the letters in unpen.