fribe rfibe firbe ifrbe rifbe irfbe frbie rfbie fbrie bfrie rbfie brfie fibre ifbre fbire bfire ibfre bifre ribfe irbfe rbife brife ibrfe birfe frieb rfieb fireb ifreb rifeb irfeb freib rfeib ferib efrib refib erfib fierb iferb feirb efirb iefrb eifrb riefb irefb reifb erifb ierfb eirfb frbei rfbei fbrei bfrei rbfei brfei frebi rfebi ferbi efrbi refbi erfbi fberi bferi febri efbri befri ebfri rbefi brefi rebfi erbfi berfi ebrfi fiber ifber fbier bfier ibfer bifer fiebr ifebr feibr efibr iefbr eifbr fbeir bfeir febir efbir befir ebfir ibefr biefr iebfr eibfr beifr ebifr ribef irbef rbief brief ibref biref riebf irebf reibf eribf ierbf eirbf rbeif breif rebif erbif berif ebrif iberf bierf iebrf eibrf beirf ebirf
Note: these 'words' (valid or invalid) are all the permutations of the word fribe. These words are obtained by scrambling the letters in fribe.