What geeks do according to xkcd

My bro sent me a link to xkcd yesterday. It's a great comic site and describes geeks really accurately.
First, what does xcfd mean?
1. My boyfriend did it a few days ago, but to the left.
2. I did it with my boyfriend a few days ago (the phone was next to his glasses). I did it with a friend recently... I don't think that's really geek though. Normal people do it too.
3. I'd never do that. That's sick.
4. I did that a lot when I was a kid. I've moved on to bigger and geekier things.
[Source]
Here are some social issues geeks face. Oh, how well I can relate!
[Source, source]
These illustrate the science obsession well. Really true.
Yep, I've caught myself thinking about math in romantic situations. That's why I only date geeks - then we can talk about it together. [Source]
Factoring time, I've never done it. But when you leave your coat at school, you can always hear a "Hey, mine's prime!". I always factor the number I get. [Source]
Geek on Wiki:
That's totally an everyday situation. [Source]
This one is really funny:
I've caught myself fantasising about SQL injection a lot recently. Too bad it's mean and illegal. [Source]