billy iblly blily lbily ilbly libly billy iblly blily lbily ilbly libly blliy lbliy blliy lbliy llbiy llbiy illby lilby illby lilby lliby lliby bilyl iblyl bliyl lbiyl ilbyl libyl biyll ibyll byill ybill iybll yibll blyil lbyil bylil yblil lybil ylbil ilybl liybl iylbl yilbl lyibl ylibl bilyl iblyl bliyl lbiyl ilbyl libyl biyll ibyll byill ybill iybll yibll blyil lbyil bylil yblil lybil ylbil ilybl liybl iylbl yilbl lyibl ylibl bllyi lblyi bllyi lblyi llbyi llbyi blyli lbyli bylli yblli lybli ylbli blyli lbyli bylli yblli lybli ylbli llybi llybi lylbi yllbi lylbi yllbi illyb lilyb illyb lilyb lliyb lliyb ilylb liylb iyllb yillb lyilb ylilb ilylb liylb iyllb yillb lyilb ylilb llyib llyib lylib yllib lylib yllib
Note: these 'words' (valid or invalid) are all the permutations of the word billy. These words are obtained by scrambling the letters in billy.