Unlocked when the player jumps into the treasure chest in the Pirate Ride.
This achievement is obtained during Act II, when Didi and Dawn are tasked with fixing the three attractions at the carnival.
While on board the ship, Tortuga’s Revenge, you will eventually come to a section where the roller coaster stops on the tracks and you need to get out. Before proceeding with the objective to turn the ride back on, head over to the stairs on the far right side of the attraction. You will notice a large black box underneath the stairs. Wait until the box opens, then quickly hop inside. The achievement will unlock right away.