Note: this requires two people
- Discover neither of you wants to decide on a particular thing (which movie you want to see, what kind of food to eat, whether or not you should get divorced, Linux or FreeBSD, etc), because both choices are equally acceptable or both parties are equally indecisive.
- Get the choices down to two1.
- One person mentally assigns a value to each choice and makes a gesture, as if flipping a coin.
- This is the cue for the other person to "call it in the air" by saying either "heads" or "tails."
- The first person then announces what the result is.
- Everyone goes along with the result.2
Essentially, you make a random number generator out of your friends. It can save you from hours of sitting around going "what're we gonna do tonight?" by allowing two indecisive people to pick and choose without really having to be decisive.
This is also quite handy for one person waffling over what to order for dinner, if you have a second person handy (heck, the waitron will do in a pinch).
It has been suggested that this is subject to 'cheating' by the person assigning the heads/tails (even in the one-person case). I don't actually see this as a problem. The original stipulation was that nobody had a specific preferred outcome - if you discover a preference while doing this, go with that preference.
This method is not generally suggested for situations where the people involved do have (different) preferred outcomes.
1 For more advanced or tricky situations, it is possible to do this with three choices; then you have the options of "heads," "tails," and "sides" (forget the laws of physics, all choices are equally possible for this purpose).
2 This is similar to how to cut cake without favoritism.