Where the grill actually unlocks
Achievement text is Grillmaster / “Start the grill”. English walkthroughs light it with the Desert Blue Shark and the NPC beside the grate. One Chinese recap puts the grill after Giant Piranha — that island is Forest, so treat that line as a mix-up. If the grate is dark, finish the shark talk, then cook.
Co-op: one cook
The grill is shared. One player watches the multiplier so nobody else dumps a second body on a 1.5x fish. Rainbow / Drip names go to the island slot machine, not the fire.