Talking Skull

The Talking Skull is a skull at the River of Forgetfulness in the Land of the Dead. When Jake goes to get a drink, the talking skull says to drink from it. Finn says the water must be bad since the skull wants im to drink it. The talking skull says "Don't drink the water", which obviously tricks Jake into drinking from it, causing him to lose his memory. Then Finn steps on the skull, carrying part of it on his foot for a while.