Here's the source:
http://www.techcrunch.com/2008/02/10/tipjoy-a-better-tip-jar-for-content/
http://www.techcrunch.com/2008/02/10/tipjoy-a-better-tip-jar-for-content/
Quote
If you leave a tip as a new user, you start to build up an account debit. You can eventually pay that off via PayPal (TipJoy keeps 2%), although no one comes after you if you choose to skip out on the bill. You can also start to ask for tips on your own site, and anything people leave for you offsets what you’ve given to others.













