I don't get it

[catalyst2]

As I was driving home from work today, I thought I saw a roo bouncing along on the side of the road. Then I realised that it was a guy in a kangaroo suit - a very good one too - and, as I drew closer, I also realised that he had a large sign around his neck saying "Kick me quick!!!!!" (and yes, there were exactly five exclamation marks too). Don't know what it was all about but he seemed to be having a great time.