You’re aight if you don’t click the disambiguation link

https://en.wikipedia.org/wiki/Pay_it_forward

I think we can keep Pay It Forward, I don’t think I knew it was a film much less an abuser-starring film.

The concept is old, but the particular phrase may have been coined by Lily Hardy Hammond in her 1916 book In the Garden of Delight. Robert Heinlein’s 1951 novel Between Planets helped popularize the phrase.