Koalas get “high” from eating eucalyptus leaves
Eucalyptus leaves while toxic, low in nutrition and high in fibre content (plus tough) are not drug-like. Koalas do have to chew slowly and heavily to break the leaf down to a pulp like consistency to obtain any nutrient value and at the same time conserve their energy due to the leaves low energy return– giving an impression of their being lethargic or “stoned”.
Interesting fact: Koalas eat up to 3 hours a day, often at night, and have special bacteria in their gut that help them digest eucalyptus leaf which would be otherwise be toxic. Mother koalas pass this via their pap to their young as part of their development early in life.