@inoru_no_hoshi the thing about riding kangaroos is an extremely Australian type of bullshitting
It involves telling outrageous and ridiculous lies, completely straight-faced
It's especially fun when you have someone to play with and riff off, like Chan and Changbin are doing here
I guess it's like improv?? You never say "no," it's always "yes, and..."
Changbin's probably spent enough time around Australians to be comfortable and join in with it.
(I assume there are other cultures where this type of silliness is also common)