How would you put an unexpected $20 to use?

[Byron Law]

OK. Currently, I am a little cash crunched as I contemplate how to best develop a passive stream of income, but I happened into an unexpected $20, so I want to use this towards getting some education (as opposed to padding the tight budget, which for the near future is going to remain tight. Something I would like to fix). A book from the Bigger Pockets store seems like a good investment of $20. I also recognize that it is not the only possibility for $20. BRRRR intrigues me. That is one of a number of possible strategies. What says the community? How would you recommend an aspiring R/E entrepreneur put Andrew Jackson to use? A book (which one)? Save it for ____? Other?