He takes a sip and then spits it out.

“I asked for a 21-year-old, this is 18 years! I’m not paying! Give me a 12-year-old cognac.”

The bartender serves him, and the man spits it out again.

“This is only 10 years! I’m not paying!”

The bartender starts getting frustrated. After more and more drinks with the same reaction, the bartender serves another one and says:

“This one’s on the house.”

The man takes a sip and immediately spits it out.

“This tastes like piss!”

“Now tell me, how old am I?”