Rum Rogers Sr. was first mate under Captain Marley on their fateful quest for the legendary treasure of Big Whoop. He died some years later in his cottage on a small island just off Phatt Island while having his bath. His skeleton was found by Guybrush in the cottage basement. True to his name, Rum had a strong affinity for rum.
Like the other members of Marley's crew, Rum Rogers held a piece of the map that led the crew to Dinky Island, resting place of Big Whoop. After LeChuck's transformation into a ghost he systematically hunted down and killed each of Marley's crewmen. Aware of Rum's tendency to toast bread while taking a bath, LeChuck simply dropped the electric toaster into the bathtub with him.
When Guybrush finally discovers Rogers' body, in a secret room in his house on Phatt Island (now owned by his son Rum Rogers, Jr.) his skeleton is still sitting in the bathtub, clinging to the map-piece. The map-piece seems to be stuck to his decayed skeletal hand as Guybrush snatches them both.