Repetition, Assertion, Deviation

Pick a topic that is familiar to all students (e.g., cafeteria food). Arrange the students in a fixed order, from first to last. The first student starts to give a speech on that subject.

Meanwhile the audience is listening for three sins: repetition (beyond that required for clarity), assertion (making a statement without any evident attempt to support it) and deviation (straying from the topic).

Once the speaker is justifiably called on one of those sins, then the second speaker stands up and continues the speech. The speech continues until it is truly impossible to say anything without repeating, asserting, or deviating.