The more people use it the bigger it gets.
If you play with it too much you can go blind.
You wouldn't believe the things people put in there!
It has no conscience and no memory.
It provides a way to interact with other people.
If you don't apply the appropriate protective measures, it can spread viruses.
The part you see is actually just the front end of a very complicated system.
Some folks have it, some don't.
Those who have it think that those who don't have it are somehow inferior.
Those who don't have it may agree that it's a nifty toy, but think it's not worth the fuss that those who do have it make about it. Still, many of those who don't have it spend all their time trying to access it.
Once you've started playing with it, it's hard to stop. Some people would just play with it all day if they didn't have work to do.