Fasting at that level is not something I'd recommend without serious preparation, it's possible to do, but you need to be sure that you are prepared to do it both physically and mentally, it can actually have profound mental effects as well as physical ones. And when you do start eating again, be careful, too much at once and you'll simply vomit it back up, you'll have to start with small meals and work your way up.
My own advice would be 'don't do it', especially not for a bet, whoever you made a bet with probably has no concept of the kind of punishment a body takes when you fast, but it's certainly not worth doing simply to prove a point.