Write a list of different subjects on small cards or slips of paper (e.g. Tennis, computers, shopping for food, traffic, beer, suits and ties, cycling, babies).
Show a subject card to one S and start an informal chat with the S without naming the subject on the card (circumlocution). Other SS write down the subject on paper (without the other SS seeing) when they think they know what it is. If they’re correct, they can join in the chat.