I got us $10 each of free bitcoin when you sign up with my invite link and buy or sell at least $100 of digital currency: https://www.coinbase.com/join/simes_en?src=android-sms
Click on the Coinbase referral link then create your account and you can start using coinbase and buying bitcoin, ethereum and litecoin. The 10$ coupon code will be automatically added to your wallet once you have trade more than 100$. You can share you coinbase coupon link & coinbase voucher to invite your friends and get 10$ of free bitcoin when they activate their account.