"The Test!" joke

A guy walks into a bar and rudely demands a shot of 12-yr old scotch.
The bartender thinks “this guy doesn’t know the difference, ” so he pours a shot of 2-year old scotch.
The patron takes one sip and spits it out. He promptly hollers at the bartender I said 12-year old scotch, you bozo! ”
Still unimpressed the bartender pours some 6-year old scotch.
The patron takes a sip…same reaction.
But the bartender still doesn’t believe the patron knows the difference. So he pours a shot of 10-year old scotch. Again, same reaction from the patron.
Finally, the bartender is convinced. He pours the patron a glass of 12-year-old scotch. The patron takes a sip and is most satisfied.
All the while this has been going on, a drunk at the end of the bar has been watching.
He slides a shot glass down the bar to the patron and drunkedly says:
“Shay mishter, tashte this! ” The patron obliges…he promptly spits it out.
“That tastes like pee!, ” he shoots back at the drunk.
The drunk replies: “It ish. Now how old am I? ”