Keep groups no smaller than 10 and have the group seated in a circle.
Have each person state two truths about themselves and one lie. For example, you might say that you had a burger for lunch (true), have two siblings (false), and like to play hockey (true).
Then have the next person in the circle decide which statements were true and which statement was false.
After the second individual guesses, the first person will reveal the lie to the group.
This is especially fun for new teams, and can be exercised over a group chat or forum (in this case, just set the order of respondents beforehand by assigning each person a number).