You won the lottery.

You stepped in dogshit and then found a 100$ bill under it?

You decided to do a $100 game giveaway and the amusing thing is us lot creating a monster sized thread guessing

Happy birthday!

You finished your studies

The company facilitating the electronic money transfer made an error resulting in too many GOGs being charged. Company owned their error and will pay for the mistake from their own monies. Now you contact GOG to request an adjustment allowing you to give away the extra's, in one form or another :)

You met Chuck Norris or someone just as awesome.
Edit: Ooooh, Russian... well... you met Vladimir Putin. And the funny part was that he was drunk and had diarrhea and crapped his pants while vomiting on a bodyguard.

You found and took a picture of the elusive four leaf clover.

You recieved a set of Matryoshka doll each neatly placed inside the other, except, instead of the smallest one you found a tiny plastic grenade/Avengers toy.

You bought a game online, but when you went to play it you found that it was a completely different game instead.

(This has actually happened to me once. I bought a used copy of Street Fighter 2 Championship Edition at Gamestop, but when I went home to play it the game somehow turned out to be Slaughter Sport <_>).

You made a level 99 hardcore Diablo 2 character?

Maybe he reached level 100... and was back at level 1. But got to keep all his skills. That would be awesome.

you found out you were adopted.

You appeared in the paper or on TV ?

it snowed, and u made a snowman :)

An old wizard (complete with massive, pointy beard/hat combination) appeared on your door step and declared that you were the Chosen One.

Then he wandered off without telling you what you'd been chosen to do.