Fun fact: Even without an Internet connection, Google’s Chrome browser offers up a pretty decent way to pass the time.
That little dinosaur atop the “Unable to connect to the Internet” message you get when you’re offline is actually a playable character in a secret side-scroller game. Just tap it (or mouse-click it from a computer) to start up the first level. From there, tapping again will make the dinosaur jump over the cacti that appear onscreen — which is the whole object of the game.
It’s not the most engrossing game on the planet, but it’s still, by far, a more pleasant time killer than talking to someone on the subway.