How would you tell your friends?
Casually mention it down the pub? Throw a massive party for everyone? Not tell them at all? Secretly do Amelie-esque good deeds for them without telling them it was you? Play horribly elaborate and expensive practical jokes on them?
I was thinking about this on the way to work, where I do most of my daydreaming about winning the lottery. I reckon I'd go for the casually mention it down the pub idea. But not until closing time so I didn't have to buy a round for everyone.