Smartphone.
Yes, that's a serious suggestion.
My Sony and the Kindle app are both on my phone, and so is my Kobo app. I also have Aldiko on there, for my Smashwords and OmniLit books. You can do nothing but read all day, and as long as you have a good poker face (and access to chargers!) you can make anyone around you believe you're reading news and sports feeds, checking Facebook, or playing lame games.
