The rules are:
There is a cookie.
It is indestructible.
You must get it with all means possible.
When you have it, you must declare that it is so.
For example:
Player 1: I steal the cookie. My cookie!
Player 2: I smash Player 1 and take the cookie. The cookie is mine now!
Player 1: I detonate a bomb and take the cookie from the wreckage. Of course, the cookie is mine.
Let's start. My cookie!