Coin Farm and Coin Birds are two websites that must be run by the same company, as they're exactly the same.
I started playing around with faucets a few years ago, and ran across these websites then.  I knew there was going to be a catch, but couldn't find what it was.  I had a little cash to spare, so I put $30 into it and let things play out.

I currently have 2,805,092 'gold bars' waiting for payout, which is more than the 2,750,000 minimum they require to withdraw using BTC.  Their withdrawal calculator puts the available BTC withdrawal at around 0.01 BTC - around $400 at the time of writing.  When I tried to withdraw, though, I was presented with this screen.

In case you didn't notice, I put $30 in and now have the ability to withdraw $12.30.  Or, I can refer people who THEN spend THEIR money, and I can withdraw more.  It's a classic pyramid scheme folks.

I am mostly writing this article just so that the information is available when people look it up.  My cursory search of "coin birds" when I found it didn't show me where the catch was.

Please learn from my simple experiment, and stay away from these sites.  Ain't nobody got time to play the referral game and put money in the pockets of these scammers.