I never heard the phrase before I saw a movie a few years ago about a young boy who would help people out or do things for them then, instead of having them pay him back, he'd ask them to "pay it forward" to someone else. There is actually an informal organization of people in our society who encourage this through bumper stickers, etc....random acts of kindness, I think is the phrase they use..It's all about doing things for other without expecting thanks or a good deed in return...you just want to encourage folks to "pay it forward" by doing something good for someone else.