This works best in a medium size group where only one or two people know the game.

A person starts by saying 'This triangle goes from x to y to z'. Basically, x, y and z may be anything - people, places, random objects, whatever you want. The rest of the group have to guess which member of the group the triangle belongs to.

This is the fun part of the game, as guesses will be run along the lines of anything from, 'well a corner of the triangle is Aberdeen, so-and-so is from Aberdeen, so it must be their triangle' to 'well, the second corner of the triangle has the same number of letters as so-and-so's name, so it must be their triangle'.

In fact the rule is very simple: the triangle belongs to whoever guesses first!