Twelve Year Old Scotch

A man walks into a bar and said to the bartender, “Give me shot of 12 year old scotch, and don’t try to fool me because I can tell the difference.”
The bartender was skeptical and decided to try to trick the man with a 5 year old scotch.
The man took a sip, scowled and said, “Hey bartender, this crap is 5 years old. I told you that I wanted a 12 year old scotch!”
The bartender tried once more this time with a 8 year old scotch.
As the man took a sip, he grimaced and said, “Bartender, I do not want an 8 year old scotch. Now give me a scotch that’s twelve years old, or I’ll leave!”
Impressed, the bartender gave him the 12 year old scotch on the house.
The man took a sip and sighed, “Ah, now that’s the real thing.”
Just then a drunk who had been watching all this, stumbled over and set a glass down in front of the man, “Hey, I think that’s really amazing what you can do. Try this one.”
The man took a sip and immediately spit it out. “Yechhh! This stuff tastes like piss!” he cried.
The drunk’s eyes lit up and said, “That’s right! Now tell me, how old I am!”