I think this is one of the oldest, yet most effective icebreakers for meetings, training, or team building sessions. The "4 Facts" exercise simply asks people to write down 4 "facts" about themselves, 3 of them true, 1 not true. We encourage participants to think of things about themselves that others don't know. We also give them license to say things that they wouldn't say in normal conversation, such as an award they won, or that they graduated first in their class in high school or college. When they are finished writing their "facts," one person will read his list, and the others in the group will try to guess the lie. When they are finished with the first person, they go on to the next, and so on. You can also give a prize for the person who guessed the most correct answers, however, this is not necessary for the effectiveness of the exercise.
The beauty of this exercise lies in helping people to learn things about each other that they might never find out in normal conversation. Unique skills or talents may also be learned. It almost never fails to surprise people, even those who have worked together for years.
The 1 untruth in the list is intended to force closer listening, and add an element of interest.
Although it is never voiced, I sometimes worry that some participants may view an exercise like this as trivial. So I will share stories of how learning more about someone created a more productive relationship. Artificial barriers to communication exist in relationships like manager-employee, engineer-craftsman, executive-everyone else, white collar-blue collar, sales-operations, and others. Breaking down these barriers is good for the organization, and an exercise like "4 facts" can help.