A man entered the bar and asked the waiter

Waiter, please, I want an 18-year-old whiskey.

And waiter handed him the whiskey, when he took the first drink, spit it out, so the man said: This is a 15 year old whiskey, I want an 18 year old.

Then the waiter came with another whiskey, which was spat again:  This is 17 years old, I want an 18 year old.

Then the waiter wondered, “How does he taste so sensitive as to differentiate the age of whiskey?”

So he decided to bring the 18-year-old, but a drunk came early and said to the guy:  Drink it.

When he drank, he spat out: Dude, this is pee.

Then the drunk answered: Exactly, that everyone knows, but do you know how old I am?