If there is no toilet paper, no bidet and no tissue paper with you, will you sacrifice your handkerchief or as a last resort, use your briefs to wipe your butt before discarding it and going "commando" until you reach home?
Your story sounds quite off as you could have easily disposed of your underwear and get a pair of disposable ones from Watsons or Guardians...either you don't travel much or u r pretty much a free sprint!