prest rpest perst eprst repst erpst prset rpset psret spret rspet srpet pesrt epsrt psert spert esprt seprt respt erspt rsept srept esrpt serpt prets rpets perts eprts repts erpts prtes rptes ptres tpres rtpes trpes petrs eptrs pters tpers etprs teprs retps ertps rteps treps etrps terps prste rpste psrte sprte rspte srpte prtse rptse ptrse tprse rtpse trpse pstre sptre ptsre tpsre stpre tspre rstpe srtpe rtspe trspe strpe tsrpe pestr epstr psetr spetr esptr septr petsr eptsr ptesr tpesr etpsr tepsr pster spter ptser tpser stper tsper estpr setpr etspr tespr stepr tsepr restp erstp rsetp sretp esrtp sertp retsp ertsp rtesp tresp etrsp tersp rstep srtep rtsep trsep strep tsrep estrp setrp etsrp tesrp sterp tserp
Note: these 'words' (valid or invalid) are all the permutations of the word prest. These words are obtained by scrambling the letters in prest.