When I first saw this object, I was attending an American School Counselor Conference conference about 10 years ago. I bought one and tried it out at our school counseling department chair and elementary facilitator's Leadership Training...and it actually worked! It was a great icebreaker. It was a way to engage colleagues in conversation and for them to self-disclose information in a controlled environment. It actually was a lot of fun! Your group forms a circle and you toss the ball to someone across the circle. When they catch it. They look at where their thumb landed and then they answer whatever the prompt states or questions asks.
You can use it for adults or students. There is even a version where you can write your own questions/statements. Great for formative assessments!
Since that time, the thumball has evolved into different versions with numerous topics. It's a great activity. Check it out below for a demonstration and a list of the different types.