Here's a photo of an ultra-orthodox Jewish man wrapped in a plastic bag in his airline seat. His reasoning (if one might apply such a word) is unclear but apparently this is done to ensure the Bagged One does not become impure in the eyes of God just in case the plane flies over a Jewish cemetery.
Yeah, I know. What do you mean the cabin is pressurized? That's no good. Gimme a giant see-through plastic bag with a breathing hole poked in it somewhere. That's how you block out the magical nasty.
Religious people are so fucking weird.