birrs ibrrs brirs rbirs irbrs ribrs birrs ibrrs brirs rbirs irbrs ribrs brris rbris brris rbris rrbis rrbis irrbs rirbs irrbs rirbs rribs rribs birsr ibrsr brisr rbisr irbsr ribsr bisrr ibsrr bsirr sbirr isbrr sibrr brsir rbsir bsrir sbrir rsbir srbir irsbr risbr isrbr sirbr rsibr sribr birsr ibrsr brisr rbisr irbsr ribsr bisrr ibsrr bsirr sbirr isbrr sibrr brsir rbsir bsrir sbrir rsbir srbir irsbr risbr isrbr sirbr rsibr sribr brrsi rbrsi brrsi rbrsi rrbsi rrbsi brsri rbsri bsrri sbrri rsbri srbri brsri rbsri bsrri sbrri rsbri srbri rrsbi rrsbi rsrbi srrbi rsrbi srrbi irrsb rirsb irrsb rirsb rrisb rrisb irsrb risrb isrrb sirrb rsirb srirb irsrb risrb isrrb sirrb rsirb srirb rrsib rrsib rsrib srrib rsrib srrib
Note: these 'words' (valid or invalid) are all the permutations of the word birrs. These words are obtained by scrambling the letters in birrs.