choof hcoof cohof ochof hocof ohcof choof hcoof cohof ochof hocof ohcof coohf ocohf coohf ocohf oochf oochf hoocf ohocf hoocf ohocf oohcf oohcf chofo hcofo cohfo ochfo hocfo ohcfo chfoo hcfoo cfhoo fchoo hfcoo fhcoo cofho ocfho cfoho fcoho ofcho focho hofco ohfco hfoco fhoco ofhco fohco chofo hcofo cohfo ochfo hocfo ohcfo chfoo hcfoo cfhoo fchoo hfcoo fhcoo cofho ocfho cfoho fcoho ofcho focho hofco ohfco hfoco fhoco ofhco fohco coofh ocofh coofh ocofh oocfh oocfh cofoh ocfoh cfooh fcooh ofcoh focoh cofoh ocfoh cfooh fcooh ofcoh focoh oofch oofch ofoch fooch ofoch fooch hoofc ohofc hoofc ohofc oohfc oohfc hofoc ohfoc hfooc fhooc ofhoc fohoc hofoc ohfoc hfooc fhooc ofhoc fohoc oofhc oofhc ofohc foohc ofohc foohc
Note: these 'words' (valid or invalid) are all the permutations of the word choof. These words are obtained by scrambling the letters in choof.