This idea was shared by Carissa Peck, in her blog, Trying to Teach.
Basically, get each student to write a relevant question in the target language on a scrap piece of paper. (You could use vocabulary items instead of questions if you want - but in either case, the answer should not be written down, just the question.)
Then, they scrunch the piece of paper up into a ball and wait for a signal from you, when everyone is ready.
then - 30 seconds of chaos while they throw "snowballs" at each other.
When time is up (I'd recommend a VERY clear signal!) each student grabs the "snowball" closest to them. Select students to read out and (try to) answer the question.
I personally like Carissa's suggestion of making it into a team competition - divide the class into two before the snowballs go flying, on opposite sides of the room. "At the end if they answer their review question right, their
team gets 10 points. If they don't get it right, let their team help
them out and if as a team they are correct they get 5 points. (Let the
other team steal after that for 5 points if you wish)"
Carissa has a couple of other suggestions for different versions on her blog. Her version in full is here. You have to admit that it would be a memorable lesson, which the "teaching the brain" theorists state is a key part to get students to remember what they learned in the lesson. Have fun!