Sherman, who resides in Mount Acidophilus, is the "lactose-intolerant" volcano god, personified by the Cannibals that lived in Blood Island. It originally erupted every evening, and was considered a famous tourist attraction throughout the Caribbean. Its lava passed the Goodsoup Hotel via a small canal and heated a specially designed barbecue, which became an attraction unto itself. The volcano mysteriously ceased erupting shortly after the Cannibals arrived.
Sherman's followers were a tribe of cannibals that originated from Monkey Island. They began making their usual human sacrificial offerings to the volcano, which did little to cease the regular eruptions. After a bit of experimenting, they discovered the volcano's peculiar "dietary" habits, declaring it to be "lactose-intolerant". They built a village at its base and began offering a regular feast of fiberous delights, which they believed helped appease the volcano's violent eruptions by feeding the volcano mannequins made from fruits and vegetables once a day. This paradigm shift would later alter the tribe's own lifestyle, turning them into "Vegan Cannibals".
Guybrush, in typical mischevous fashion, tossed some cheese during a sacrificial ceremony. This caused the volcano to erupt, leaving a scorching river of lava flowing across the island.