Pokemon GO or any other game.
This only works ONCE so use the money wisely.
Video for proof and instructions:
First step: Download Whaff on your mobile phone.
Second step: Login with your Facebook account.
Third step: When it asks you for the code, use the special referral code (this is very important because it's a special code) -.
Fourth step: Also a very important step, you must reinstall Whaff and login again with your Facebook account in order to receive the money.
The money will be on your account in 5 - 10 minutes after doing all the steps.
You can receive the money on Paypal or Google Play Giftcard.