This isn’t your by-the-book Spanish term. If you know Spanish, then you’d most likely have heard this slang phrase in reference to a specific thing, like Puro Pinche Spurs or Puro Pinche Derby. It translates to phrases like “Heck Yes” or “F*ck Yes.” It enhances an adjective.
Puro (pure) and pinche (f*cking) in my case refers to any fun thing you’d like to do a heck of a lot of, e.g. Puro Pinche Party, Puro Pinche Music, or Puro Pinche Drinking.
I hope this helps. You can always use urbandictionary.com to look up any slang terms not quite understood here. Feel free to drop the phrase “Puro Pinche” in public wherever you go :)