A Priest is teaching the natives to speak English. He points to a tree and says to the chief, "This is a tree."
The chief says, "Tree."
The Priest is pleased and points to a rock, "This is a rock."
The chief says, "Rock."
The Priest hears rustling in the bushes. They peek over and see a couple of having sex. The Priest is flustered and says, "Man riding a bike."
The chief looks at the couple, pulls out his blowgun and kills them. The Priest goes ballistic and yells at the chief he's spent years teaching the tribe how to be civilized and be kind to each other, so how could he kill these people in cold blood?
The chief replied, "My bike."