go to [url=https://gitcoin.co/townsquare/?cb=ref:f8cc]gitcoin[/url] and join with your github account.
Isn't this a ref link?
But still, just to be clear. I give you 0.005eth and after my contribution I get 0.01ETH back. So you double my contribution. And after Just like that? Blah, blah, blah...