1 Me: {pointing at the reader} I challenge you! Rock, Paper, Scissors! Best of three!
2 {scissors}
3 {paper}
4 {rock}
5 {thinking suspiciously}
6 Me: {glaring at the reader} Are you sure you're not cheating?

Rock, Paper, Scissors is a simple game of chance. I'm sure most of you are already familiar with it. The interesting thing is that if you play an extended series of games with a single opponent, and they use any non-random method of choosing what symbol to play next, then it's possible to exploit that and increase your own odds of winning to more than 50%. As such, far from being a trivial child's game, Rock, Paper, Scissors is an important and well-studied example in the highly mathematical field of game theory.

If you prefer a good laugh to complicated mathematics, check out the World RPS Society.

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2016-05-09 Rerun commentary: I was sitting and looking at this strip, pondering what to write for the rerun annotation, when my wife walked by and her attention was attracted to it. After reading the strip over my shoulder she asked, "Do you have to practise and take multiple shots to get those expressions, or do they just come naturally to you?"

Oh, and I should qualify the above statement about being able to exploit your opponent's non-randomness to raise your chances of winning above 50%. This assumes your opponent is choosing their plays based only on their own internal ruminations, and not attempting to do exactly the same sort of analysis to your plays.