The rules are quite simple, and quite fantastic for this game:

First, a person or thing is named. Then, in the following post, the next person has to say who or what can defeat the stated person or thing. It doesn't have to be anywhere near remotely true; You just have to explain yourself briefly or thoroughly. Then you can name the next person or thing to be defeated.

Example:

A used car salesman.

- Defeat him by wearing earplugs. All of his power is in his pitch, and how is he to sell to you if you cannot hear him? He'll be powerless.

Got it?

Okay, first person or object is:

A rabid dog