Petra Polis (also called Pierre et Paul) is a very simple game meant to be played by a medium-sized group of people, say from 5 to 20. It takes very little time to teach or learn (and even less time to master), can be played virtually anywhere, and is, in general, a lot of fun.
To begin, one person is assigned the role of Petra and another the role of Polis. Everyone else is then assigned a number, starting at 1.
The game is basically an emphasis on concentration. The group begins clapping out a standard 4/4 time (preferably starting slow, and speeding up as the game goes along.) The turns always go on the 1 and 2 beats. To play, you simply say your name ("Petra" or "2" or whatever) and then another player's name. It then becomes their turn.
The object of the game is to make someone mess up. If they do mess up, they move to the end of the line, and everyone else moves up. If they mess up and they are at the end of the line, they're out of the game. Play continues until one person is left. Capisce?
For this tutorial, we will have 6 people playing. They are named Alex, Brian, Chris, Dana, Eleanor, and Fran. Here is the lineup so far:
Alex: Petra
Brian: Polis
Chris: 1
Dana: 2
Eleanor: 3
Fran: 4
Here goes the game:
Alex: "Petra, Polis" *clap* *clap*
Brian: "Polis, 3" *clap* *clap*
Eleanor: "3, Petra" *clap* *clap*
Alex: "Petra, 1" *clap* *clap*
Chris: "1, Polis" *clap* *clap*
Brian: "Polis, uhh.." *ERRR*
Brian moves to 4, Fran up to 3, Eleanor to 2, Dana to 1, and Chris is the new Polis.
Alex: "Petra, Polis" *clap* *clap*
Chris: "Polis, Petra" (sometimes this can go back and forth a looooong while) *clap* *clap*
Alex: "Petra, 4" *clap* *clap*
Brian: "Polis, CRAP!" *ERRR*
Brian is now out of the game. Play continues.
Remember to speed up! It's what makes the game a lot of fun. Also, you might want to have a practice round where you go straight through the line up ("Petra Polis", "Polis 1", "1 2", etc ...) to give everyone an active refresher course. Enjoy!
Apparently some people also play this as a drinking game. I'm a minor; I still wouldn't know.
Thanks to mkb for the Pierre et Paul thing.