An Irishman found a magic lamp...
... He picked it up, gave it a rub, and out popped a genie.
"Master! you have freed me from the lamp! I will grant you three wishes!"
"Wow, three? Okay, let me think for a moment."
After a short period of deliberation, the Irishman had finally come up with something.
"I would like to have a pint of Guinness that magically fills all the way back up when I've finished it."
"Your wish is my command!" booms the genie, and suddenly in the Irishman's hand is a pint glass full to the brim of Guinness.
The man takes a few swigs to test it, likes what he's been given, and continues to down the rest of the drink. As soon as it was empty, the glass magically filled right back up with a fresh pint, which he also enjoys immediately just to see it fill up again. Infinite Guinness.
This happens a few more times before the genie starts to become a little impatient. "... Master, what may I grant you for your second and third wish?"
The Irishman wipes his mouth, takes a look at the glass in his hand and says, "Well, ... I'll have another couple of these of these to put in my pockets, just in case I break the glass when I fall over drunk."