This has to do with free offer sites such as ZNZ. I know some of you probably cringed when you read that, and I'm really not a fan of them myself. Honestly I was just bored one day and wanted to try something new. The fact is, you can make some fast cash this way. There are people that actually make pretty good money.
These sites are really just a unique spin on incentive CPA offers. People will pay you some pretty decent cash to be their referral. Once you complete the offer requirements, which should only take you 30 min or an hour, the cash is sent to your paypal account. This is called "cash for referral." If you choose to continue from that point, you can get paid daily for your own referrals.
That's all there is to it... Again I don't recommend this as a business model. I haven't done it since, but I used that extra cash to buy some banner ads! It's up to you how you want to make your money, there are tons of options out there.