contra-example
The opposite of an example, tells the audience how NOT to do something.
Teacher: Be attentive when our guest speaker is giving their speech
Student lounging with their phone at the back: Whut do u mean be attentive?
Teacher, irritated: Well a contra-example will be acting like you
Student lounging with their phone at the back: Whut do u mean be attentive?
Teacher, irritated: Well a contra-example will be acting like you