If it's just a recent thing phoenix and your cats are used to their food it could be that they have been 'dining out' and have munched on a bird or mouse.
I've owned lots of cats but never had any that parped. Even the ones that lived to a good old age. My elderly dog however, sounds like someone letting air out of a balloon We, childishly get the giggles but he just lays there oblivious.
It's usually an older age thing though. As I can vouch for
Love the name Oliver Sprout
Another week, another Tory MP sex scandal!
To think that London, or anywhere else for that matter, does not belong to any one demographic