On your phone, if you to Extras and click on Stats, there's a large amount of information about your various statistics about your game.
On page 10 of 11 at the top of the page, there are two statistics that read as follows:
Cat & Mouse: Most Points Earned: 0
Cat & Mouse: Cash Earned: $0.00
I've finished the main campaign, and I'm currently working my way through the diversions. I've not heard any mention of "Cat & Mouse" at all. I know it's not a diversion.
What is this? Is it something that is co-op only (I've only played single player)?