I tend to avoid games in math class because they usually just reward the kids who can think the fastest. Trashketball is a little different.
Kids are in teams of 2-3, a question is posed, and students work together to answer it. Only one person can write on the dry erase board per question. Students who answer correctly, get a chance to shoot a trashket (wadded up paper into the garbage). Different distances from the garbage are worth different points. Next question is a different person writing on the dry erase board and the game continues.
I got this idea from Jennifer Gonzalez at the Cult of Pedagogy