Well I’m not sure what facebook are doing with this but if you follow the following commands you get a lens flare (a visual effect) on the screen:

1. Log into facebook
2. Click on the background (the white bit)
3. Press: up, up, down, down, left, right, left, right
4. Press: b, a, enter
5. Click on the screen

Thanks facebook - I guess their code monkeys have got time to kill !?

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