The real McCoy is a phrase which means the genuine article, the real thing. Though the origin of the phrase the real McCoy has been attributed to the famous Hatfield and McCoy feud which raged in the West Virginia and Kentucky areas of the United States in the late nineteenth century, it most certainly has its beginnings in a Scottish phrase. McKay was a popular brand of whiskey in Scotland in the 1850s, and references to “the real McKay” are found in newspapers throughout the country in the 1850s and 1860s. By the 1880s, the phrase is found in Canadian literature as the real McCoy, meaning anything or anyone that is the genuine article or the real thing.
You’re not the real McCoy (or James Kirk), BA tells Trekkie Alex (The Belfast Telegraph)
This is the real McCoy, however, fresh off the boat at Tilbury, and Hyundai allowed us free reign to drive it wherever. (The Telegraph)
The captain originated the phrase “the real McCoy” because he claimed to never pay for protection from law enforcement or the mob, and always delivered uncut liquor. (Entertainment Weekly)
Monterey City Community Services Director Kim Bui-Burton told the Monterey County Weekly that officials are looking for a specific mark made by the statue’s artist Wah Ming Chang to determine if they have the real McCoy. (The Huffington Post)
Well, he’s the real McCoy, as he went out of his way to demonstrate, not just by separating himself from his “Colbert Report” persona, but by repeatedly acknowledging his family, especially the members present in the audience: his wife and children, as well as his brother. (The Wellesley News)