im pretty scared of kangaroos, half of them are like cute little rabbit dogs and then there's randomly some of them that are like, steroid-jacked dog murderers with a secret tailspring disemboweling kick attack, the fact that the scary ones exist and are the same species as the cute ones means that you can never be sure if interacting with the cute ones will attract the ire of the scary ones. their physiology is way different from other mammals, if a kangaroo invented a car it would not have wheels but gigantic spring loaded skis and you would pilot it from a dark and warm mucosal sac. i actually think that the tall aliens in halo are probably canonically kangaroos