A combination of the two insults Peacho and Kuffar. A Kupeacho is someone who fails at everything they do. To call someone a Kupeacho is very serious indeed, considering that a Kupeacho is even more incompetant than a regular Peacho.
"Man, I thought he was a Peacho before, but now I think he's a complete Kupeacho."
Someone who excels at life. In the context of videogames, Peacho Killa can be used a as by-word for "Pro"
However, Peacho Killa is a name that can describe anyone who has excellent skills in any activity. Peacho Killas metaphorically kill Peachos in their spare time.
J- "I saw some Peachos walking down the street the other day, know what I did? I blew their fucking brains out with my glock! Got brains all over my nice shirt too."