How can I avoid having to use the bathroom during a long plane trip?

New York to Rio(Brazil)....I'm always in the window seat boxed in by sleeping parents and older sister sits in next row(shes in high school). I'm shy/embarrassed about having to make scene about going on the plane.How can I avoid having to use the bathroom during a long plane trip?The only way to reduce the amount of times you need to go the bathroom is to drink less. You will probably need to go at least once on the plane ride.