The thoughts of a shy guy:
"Wow, that girl is really pretty. Maybe I should go talk to her. No, I'll look like an idiot. But she's so-oh crap, she's coming this way. Shit shit shit, she just sat down next to you. Say something, you moron. Do it. For god sake! Crap, you waited too long, now if you say something, it's gonna be awkward! You missed the window fuck head!"
Girl:"Ummm, hi"
Shy guy: "Hi."
Thoughts: "Hi? That's all you could muster up, you couldn't at least go for small talk or something? Just die, right now."
True story. Seriously, the best way to deal with a shy person is to force them to talk. Usually they want to but just can't figure out how to start.