The real McCoy
Definition 1 of 1
Pro Tip 1/3Origins matter
Understand that 'the real McCoy' originated from historical references, giving weight to its authenticity. 
After trying various colognes, I finally found the real McCoy at a vintage store.
Pro Tip 2/3Emphasize authenticity
Use it to stress that something is not a copy or imitation, often with a tone of relief or satisfaction. 
We've had many speakers, but she's the real McCoy, truly inspiring.
Pro Tip 3/3Avoid overuse
Use sparingly to maintain the phrase's impact, especially in formal or serious contexts. 
Out of all the signatures, this one's the real McCoy.