are out in the middle of a lake, fishing.

O'Brian spies an empty wine bottle floating past and retrieves it. Upon his removing the cork, a Genie pops out. Looking about the boat he says "You boys are Irish, aren't you? In which case I shall grant you but one wish."

Without missing a beat O'Brian blurts out " I wish this whole lake was Guinness."

The Genie snaps his fingers and disappears back into the bottle. The boys look around and sure enough, the whole lake is Guinness Stout. Murphy turns to O'brian and says " Jayzus lad, what the hell were ya thinkin'? Now we're gonna have to piss in the boat."