tirrs itrrs trirs rtirs irtrs ritrs tirrs itrrs trirs rtirs irtrs ritrs trris rtris trris rtris rrtis rrtis irrts rirts irrts rirts rrits rrits tirsr itrsr trisr rtisr irtsr ritsr tisrr itsrr tsirr stirr istrr sitrr trsir rtsir tsrir strir rstir srtir irstr ristr isrtr sirtr rsitr sritr tirsr itrsr trisr rtisr irtsr ritsr tisrr itsrr tsirr stirr istrr sitrr trsir rtsir tsrir strir rstir srtir irstr ristr isrtr sirtr rsitr sritr trrsi rtrsi trrsi rtrsi rrtsi rrtsi trsri rtsri tsrri strri rstri srtri trsri rtsri tsrri strri rstri srtri rrsti rrsti rsrti srrti rsrti srrti irrst rirst irrst rirst rrist rrist irsrt risrt isrrt sirrt rsirt srirt irsrt risrt isrrt sirrt rsirt srirt rrsit rrsit rsrit srrit rsrit srrit
Note: these 'words' (valid or invalid) are all the permutations of the word tirrs. These words are obtained by scrambling the letters in tirrs.