Start off by telling people you are running call of cthulhu, don't say anything more.
Once they arrive, start making characters, converting those feline character trait names to something more human-esque, then when they all have their character made tell them the reason they made characters so weirdly is because they will not be playing call of cthulhu, but instead they will be playing call of cthulhu (make em confused). Wait 3 seconds, then reveal the cover image and watch them hate you! :D (make them rename their character traits to be more feline if they don't suit)
Trolling aside, I played this as a get together with a group that I played keeper in a call of cthulhu whom I haven't played with for over a year. To make the feeling ever more nostalgic, I created a small scenario based off the first scenario in the call of cthulhu 6th ed. rulebook. Had the first contact be the landlords pet cat be all worried about his humans worry about the humans that go into the house, made up animal contacts at all the key locations from that first scenario in the book and got the players to go inside the dreaded house they had managed to accidentally burn down the first time (Yeah. It was an interesting group of characters). I managed to bring them around the house, pointing out key things that they had investigated before and even made guest appearances of their old characters. It was awesome. Them being cats made it even more awesome!
For those of you looking to play a more lighthearted version of call of cthulhu, maybe break up a tough and depressing campaign or maybe a player is missing one day, pull this out and everything becomes so much better.
All in all my party really enjoyed the nostalgia session, and I'm sure their cat characters will see more action in future call of catthulhu (and potentially guest starrings in call of cthulhu!).
[5 of 5 Stars!]