The Icebreaker is a question that people can answer. The answers to the Icebreaker are seen when you hover over a person's Avatar with your cursor.
The Icebreaker question feature is a great for:
team members to share something more personal about themselves
event guests to say what they're interested in
workshop participants to say what they expect from a workshop
...
How to set an icebreaker question
Here's how to set an icebreaker question:
Click on the Menu button (icon with three lines in the bottom left corner)
Click Fun Stuff
Click Icebreaker
Toggle the Icebreaker question button
Enter an icebreaker question of your own or look for one in the gallery
Notes:
Keep in mind that when you set an icebreaker question, people will need to go to their profile (Menu > Account Settings > My Profile)