tough otugh tuogh utogh outgh uotgh toguh otguh tgouh gtouh ogtuh gotuh tugoh utgoh tguoh gtuoh ugtoh gutoh ougth uogth oguth gouth ugoth guoth touhg otuhg tuohg utohg outhg uothg tohug othug thoug htoug ohtug hotug tuhog uthog thuog htuog uhtog hutog ouhtg uohtg ohutg houtg uhotg huotg toghu otghu tgohu gtohu ogthu gothu tohgu othgu thogu htogu ohtgu hotgu tghou gthou thgou htgou ghtou hgtou oghtu gohtu ohgtu hogtu ghotu hgotu tugho utgho tguho gtuho ugtho gutho tuhgo uthgo thugo htugo uhtgo hutgo tghuo gthuo thguo htguo ghtuo hgtuo ughto guhto uhgto hugto ghuto hguto ought uoght oguht gouht ugoht guoht ouhgt uohgt ohugt hougt uhogt huogt oghut gohut ohgut hogut ghout hgout ughot guhot uhgot hugot ghuot hguot
Note: these 'words' (valid or invalid) are all the permutations of the word tough. These words are obtained by scrambling the letters in tough.