One day, in the Outback...

A koala was sitting in a tree smoking a joint when a lizard walks up and says "Hey koala what are you doing?"

The koala answers, "Smoking a joint. Come on up and have some." So the lizard climbs up and the two share the joint.

After a spell, the lizard starts getting dry mouth and excuses himself to a nearby river to have a drink. Unfortunately, the lizard is so stoned, he leans over too far and falls in.

A crocodile notices this and swims out to rescue him. When they get onto dry land, the croc asks, "What's wrong with you, lizard?" The lizard tells him that he was smoking a joint with a koala, and he got too stoned and fell in while taking a drink.

The croc decides he has to see this for himself, so he asks the lizard to take him to the koala.

When they get back to the tree, the croc looks up at the koala and says "Hey, koala!"

The koala looks down and says, 

"Du-u-u-ude! How much water did you drink?"