An Irishman walks into a bar. He orders two pints of Guinness, drinks them both, and then leaves.

The next day, the Irishman returns, orders another two pints of Guinness, drinks them both, and then leaves.

He continues to do this for some time, when one day the bartender questions him, “How come you always order exactly two pints?”

The Irishman replies, “well, you see my brother and I used to go out drinking every night, but he lives across the country now, so every night, I order two drinks. One for myself, and one for my brother.”

Things remain the same for a while until one day the Irishman comes in and orders only one Guinness. The bartender becomes concerned and asks him “how come you’re only ordering one? Did something happen to your brother? Is he ok?”

The Irishman replies, “of course not, my brother’s fine. I just quit drinking”