Ballot Ballet Achievement in Hail to the Chimp

Start up a VS. game, and take control of all 4 players, and load up any map and choose "A Clam in Every Pot." Run around the map collecting clams. Once you have some collected, run to each of the pots, and press to put clams in it until the flags sprout up in your character's color, which claim it for you. Once all are claimed, let the game end, the the unlocking will be yours to enjoy.