In its simplest form, a game for two players who simultaneously each choose exactly one of the three choices, Rock, Paper and Scissors. The winner is decided by saying that Rock blunts/beats Scissors, Paper wraps/beats Rock, and Scissors cuts/beats Paper.
There are several variants, some more abstract than others, some more "balanced" than others. At its heart it relies on a non-transitive relationship, sometimes also called a "vicious circle/cycle".
A winning example: http://dan.egnor.name/iocaine.html
(from that page) Iocaine Powder's basic meta-strategy is simple: Use past performance to judge future results.
Well... The dead don't iterate.
From the Ypres1914 sketch:
Major: ...I think, I think fisties would be best. OK, so hands behind backs. After three, OK, one, two, three. (everyone except the padre who has no arms puts out clenched fist) Now what's this... stone, stone, stone, (looks down at his hand) and scissors. Now. Scissors cut everything, don't they?
Sergeant: Not stone, sir.
Major: They're very good scissors.
From a HarryHill?
(harry and alan put their hands out, harry's is paper , alan's is scissors)
Alan: ha ha my scissors cut your paper
Harry: this isn't paper, it's a layer of sedimentary rock. I win!
From a world of warcraft forum:
I am paper, rock is fine, nerf scissors!
And, as odd as it sounds, this is a console management strategy that we use in a RealTime
system to avoid PriorityInversion
There's actually a whole spec doc that explains in detail how the problem arose and how the solution came to be.
Damn. Ruined a perfectly good off-topic page.