Invisible, Senile cats

I'm cat sitting at the moment.

A friend has gone away for a week they asked their neighbour to pop in and feed the cats - no problems there except that the neighbour has had to go away for two days too. So I got asked to look after the friends two cats and the neighbours cat too for the two days he was away. Are you still with me here??

So I go into my friends house and sort out the cat food, water and cat litter and realise I have never ever seen her cats in any of the visits I have made to her house. Second visit of the day has the food gone and the cat litter stinky so I'm assuming their cats are invisible or it's an elaborate hoax!

The neighbours cat is a different kettle of fish. He was so pleased to see me and was very vocal about wanting food as he met me in his kitchen. Second visit of the day I'm greeted by a black cat shouting at me whilst it sits in the door way. I'm at a bit of a quandary now. Is it the same black cat or am I about to let a strange cat into the house. I slip in leaving a loud cat outside and put the food down and wait. My logic is he can get back in the cat flap which has a magnetic lock so only the right cat can get in. 5 mins later no cat inside but lots of meowing at the front door. I eventually give up let the cat in and it goes straight to the food bowl like it knows where it is.

I text my friend the above picture and repeat the story and get told yes it's the right cat he just has senile moments and forgets about the other ways into the house. I also tell her I haven't seen her cats and she says it's ok they have been spotted on the baby monitor they left running upstairs.

I'm not sure which is more amusing the senile cat or the invisible ones.