Description

Separate the participants into two groups, Team A and Team B, and put the participants together to sit opposite to each other. Leave the subject open and let Team A begin first. In turns, each player will talk and will say whatever they want, whatever that is. Team B will not speak and will not react to anything, they will only listen to the others. When the first team is finished, Team B will do the same.
Finally, have a discussion with the teams and ask them how it was. There may have been something that someone in Team A said and someone from Team B disagreed, but could not express it and had to wait until their turn came to say it.

Variations

This game can become much more intense and interesting when you have a topic for discussion. It could have been something that would force the participants to react and confront but they will not be able to do it until their turn comes.
Something else that would be interesting enough is to set as a theme this: "Tell us about you, who you are?" and you have 5 minutes to talk about yourself without anybody else talking or reacting.