This is TravelMoreRoads Binder Clip Tip #2. See the rest here:
http://travelmoreroads.com/10-uses-for-binder-clips-while-traveling/
Clip a trash bag to the seat back pocket on a plane, train, or bus to avoid the annoying scramble to find all your trash or dig it out of the pocket when the flight attendant comes by with the trash bag or you hear your stop announced. Leftover produce bags or newspaper bags are a perfect size. Also works well while picnicking (a great way to enjoy the weather in a new city or to save money on food while traveling).
http://travelmoreroads.com/10-uses-for-binder-clips-while-traveling/
Clip a trash bag to the seat back pocket on a plane, train, or bus to avoid the annoying scramble to find all your trash or dig it out of the pocket when the flight attendant comes by with the trash bag or you hear your stop announced. Leftover produce bags or newspaper bags are a perfect size. Also works well while picnicking (a great way to enjoy the weather in a new city or to save money on food while traveling).