yufts uyfts yfuts fyuts ufyts fuyts yutfs uytfs ytufs tyufs utyfs tuyfs yftus fytus ytfus tyfus ftyus tfyus uftys futys utfys tufys ftuys tfuys yufst uyfst yfust fyust ufyst fuyst yusft uysft ysuft syuft usyft suyft yfsut fysut ysfut syfut fsyut sfyut ufsyt fusyt usfyt sufyt fsuyt sfuyt yutsf uytsf ytusf tyusf utysf tuysf yustf uystf ysutf syutf usytf suytf ytsuf tysuf ystuf sytuf tsyuf styuf utsyf tusyf ustyf sutyf tsuyf stuyf yftsu fytsu ytfsu tyfsu ftysu tfysu yfstu fystu ysftu syftu fsytu sfytu ytsfu tysfu ystfu sytfu tsyfu styfu ftsyu tfsyu fstyu sftyu tsfyu stfyu uftsy futsy utfsy tufsy ftusy tfusy ufsty fusty usfty sufty fsuty sfuty utsfy tusfy ustfy sutfy tsufy stufy ftsuy tfsuy fstuy sftuy tsfuy stfuy
Note: these 'words' (valid or invalid) are all the permutations of the word yufts. These words are obtained by scrambling the letters in yufts.