I believe here is that Japanese Company that sells disposable underwear (for men & women):
http://www.jui-sheng.com/
It says: "Convenient, Practical, and Comfortable... Hi-Jean Disposable Briefs are as soft as silk and very essential, practical, convenient and hygienic for travelling, field camping, sports and during hospitalisation. Also...for unexpected overnite guests."
Free Delivery Worldwide. About $3 to $4 for 7 pieces.