brik rbik birk ibrk ribk irbk brki rbki bkri kbri rkbi krbi bikr ibkr bkir kbir ikbr kibr rikb irkb rkib krib ikrb kirb
Note: these 'words' (valid or invalid) are all the permutations of the word brik. These words are obtained by scrambling the letters in brik.