Act overly interested in their news. Use an exaggerated tone, a surprised facial expression, or a gasp. If they sigh or roll your eyes, follow up with dramatic, frantic questions: “Tell me! I can’t take it anymore. What is it?”
Just make sure that whatever surprising fake fact you pick, it won’t genuinely upset the other person. If you know this person is self-conscious about their grades, for example, don’t loudly ask if they failed a test.
Again, before you use this one, just make sure it won’t hurt the other person’s feelings. Ask yourself whether or not this friend enjoys a silly jab. To get a read, consider whether you two have a history of joking like this with each other.