Where did the phrase The real McCoy originate?

Answer 1

An American boxer named Norman Selby (1873-1940) adopted "Kid McCoy" as his professional name and used the phrase "The Real McCoy" to distinguish himself from another fighter named "McCoy." Although not certain, this appears to be the origin of the phrase, which expanded into American English to mean "the genuine article."

Answer 2

The phrase "The Real McCoy" refers to "the real thing" or "the genuine article"

Answer 3

There are quite a few theories as to the origin of this phrase. You can review them at the Related Link