Two Irish guys are fishing. The first guy reels in his line and sees that he's snagged an old bottle. As he's taking it off the hook, a genie pops out of the bottle.

The genie says, "Ahh! That's great. I was trapped in there for centuries. I have to give you one wish."
The Irish guy says, "Turn the lake into beer."
The genie says "Done..." He waves his hand, and the lake turns into beer.
The Irish guy says to his pal, "So what do you think?"
The second guy says, "I think you're an a--hole. Now we have to piss in the boat."