Dog 1: What’s the worst thing to happen to this planet?

Dog 2: Duh. I dunno.

Dog 1: I’ll give you a hint. It walks on two legs…

Dog 2: Ducks?

Dog 1: It’s cruel…

Dog 2: Oh!

Dog 1: It’s destructive…

Dog 2: Oh, Oh!

Dog 1: It has a heart of coal…

Dog 2: Oh, Oh! I know! Humans!

Dog 1: Right answer. And here’s your prize.