The washcloth trick refers to a popular travel hack where guests place a damp or rolled-up hotel washcloth across the gap at the bottom of their room door to block hallway light from shining into the dark room, or to prevent drafts. Additionally, frequent travelers sometimes use washcloths draped over smoke detectors or tucked into security latches as makeshift privacy or safety measures, though hospitality professionals generally advise relying on standard built-in door locks and security features.