You have two options depending on how imaginative you are feeling right now:
Write from either the observer’s or kangaroo’s perspective to tell a story. What happens next? Who moves? How do you feel? What sounds can be heard? Why is s/he there? Are reinforcements required? A vet, a zookeeper, a friend?
Alternatively, list 5 facts about kangaroos, or 5 ways to defend yourself against a kangaroo. If you are stuck, read this to boost your motivation.