Even when you know the people you're talking to, you may get some surprises after a while. A lot of people get sucked into this virtual world of ours, and want more than we are willing to give. This happens to relatively well adjusted people as well. A lot of people have had bad experiences online. Harassment is happening on the net, even between complete strangers.
Some people latch unto anyone they can reach, because they like harassing people.
This could happen in chat rooms, and other parts of the net. That said, online chat's are great when structured and kept on a theme that isn't too personal, or between friends in real life who moved too far away from each other. I'm sure every celebrity has heard about this phenomenon. On the internet it's closely linked with harassment, sometimes that's what it is, sometimes it's just another way of stalking a victim. The interesting part is that it isn't limited to celebrities.