Beer Lake.

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 and promises to grant him one wish. "Turn the lake into beer," he says. The genie goes "Poof!" and the lake turns into beer. He says to the other guy, "So what do you think?" The other guy says, "You jerk. Now we've got to piss in the boat."