What is a rare Pepe?

Excuse me, could you please elaborate on the term "rare Pepe"? I've heard it mentioned in the context of digital collectibles and memes, but I'm not entirely sure what it entails. Is it a specific type of digital artwork or a limited edition item? How does one acquire a rare Pepe, and what kind of value does it hold in the cryptocurrency and finance world? Additionally, could you discuss any potential risks or concerns associated with investing in or trading rare Pepes? Thank you for your time.