how to stop my niece going on Facebook?

[Paddy]

What about this: Next time you see her, just say she can do whatever she wants on the computer, and that you don't care, however, she won't know that you'll be secretly spying on what she is doing whilst on Facebook, IF she does anything bad, then sit her down, and shout at her, if that doesn't work say you're going to take a picture of the messages and send it to her parents, who will then send it to her friends parents... If she wants Facebook, then she won't be naughty on it...

The simple way: say that you're going to get her parents to tell her friends parents about this, which would: 1. Embarress her..... 2. Will hopefully be supervised when going round a friends house and on laptop... TRUST ME, as a 12 year old myself I know that I wouldn't want to be embarrassed in that way, so I'm nearly 1000000% sure she wouldn't to. :-)