You need plenty of cold beers and also the Battleship board game. You place the ships where you want to and then you begin the game (same rules apply like misses, hits and sinks).
Here is how it works. The first player guesses where the opponents ship is. If they are wrong the person who guessed has to drink, if they were right and they have a hit, the other player has to drink.
You do this throughout the whole game (rarely putting down your beer). When you sink a person's ship they have to drink double of what you sunk. Therefore if you sunk their 5 ship they have to drink 10 drinks. By the time your finished you won't even be able to say "you sunk my battleship".