"Today's title grudge match at Extreme Kangaroo Boxing Stadium is between Kang 'The Man' Hopper, and Red 'The Iron Rustbucket' Roo."
I'm not sure whether this little dust up was merely play between these two red kangaroos, whether it was a battle for supremacy, or whether it might have been a little bit of both. I suspect the last, although the zoo seems to be well aware of the need to keep genuinely competing males apart.