DS Morris Code
The DS is a very versatile gaming console from Nintendo. I once saw a group of kids on a plane develope their own special secret code and use it to communicate with eachother. While I think it is a rather immature for grown adults to be communicating in such a manner on a grown up environment like an airplane. I still think that with the right R4 DS, the appropriate software emulation can be tweaked as to include a sort of morris code. I believe that the DS does have Wi-fi capabilities so this should not be too much of a stress.