Generally, to make learning more fun, I use some small comedies or very short stories in correlation with the concept, when the similarity or the analogy permits. It gives a great success to make students happy, focus, love the course, be relaxed from their internal stress, etc.
However, we must be vigilant, we risk to lost control, especially with some students who go far away. We must keep a discreet watch on their reactions or behaviors instantaneously. It’s very hard, it makes me very tired, but very successful.