His parents were runaway slaves and he's a testament to the saying, "It doesn't matter where you come from." Elijah McCoy's humble beginnings didn't prevent him from making his mark on the world. An inventor, McCoy was responsible for 57 different patents and the saying, "the real McCoy."
Plain and simple, the real McCoy means the real thing. It's a symbol of excellence. McCoy worked as a fireman and oilman on the Michigan Central Railroad. As an oilman, he was responsible for making sure the train was well lubricated. After a few miles they had to stop the train while McCoy reapplied oil to the axles and bearings.
That changed in 1872, when he developed and patented the lubricating cup that could automatically drip oil when and where it was needed. Orders came rolling in for McCoy's lubricating cup from all over the country. It revolutionized the industrial machine industry. It was so popular, people inspecting new equipment would ask if the device contained the real McCoy. He also invented the ironing board and the lawn sprinkler.