One of the few joys of taking transit instead of driving yourself somewhere is the ability be on your phone without threat of a ticket or killing someone. That being said, if you're going to check your phone every 10 seconds while you're sitting next to someone, don't keep putting it back in your pocket!
The guy next to me on the train this morning clearly didn't understand this idea. He was playing some sort of game on his ipod, but had a separate phone that he kept checking. Since his hands were busy with his game though, he kept putting the phone back in his pants pocket, which meant he also kept jabbing me with his elbow. Seriously, dude, is your lap broken? Because you could save us both the trouble and just leave it there.