durst udrst drust rdust urdst rudst dusrt udsrt dsurt sdurt usdrt sudrt drsut rdsut dsrut sdrut rsdut srdut ursdt rusdt usrdt surdt rsudt srudt durts udrts druts rduts urdts rudts dutrs udtrs dturs tdurs utdrs tudrs drtus rdtus dtrus tdrus rtdus trdus urtds rutds utrds turds rtuds truds dustr udstr dsutr sdutr usdtr sudtr dutsr udtsr dtusr tdusr utdsr tudsr dstur sdtur dtsur tdsur stdur tsdur ustdr sutdr utsdr tusdr studr tsudr drstu rdstu dsrtu sdrtu rsdtu srdtu drtsu rdtsu dtrsu tdrsu rtdsu trdsu dstru sdtru dtsru tdsru stdru tsdru rstdu srtdu rtsdu trsdu strdu tsrdu urstd rustd usrtd surtd rsutd srutd urtsd rutsd utrsd tursd rtusd trusd ustrd sutrd utsrd tusrd sturd tsurd rstud srtud rtsud trsud strud tsrud
Note: these 'words' (valid or invalid) are all the permutations of the word durst. These words are obtained by scrambling the letters in durst.