'Feeling a little off colour puss?' was the headline for a story in the Daily Mail, about a cat (puss) in Varna, Bulgaria, who appeared to have turned green.  At first, people thought it might be radioactive, and then that it had been attacked and painted by vandals, but it turned out that it had simply been sleeping on the top of an abandoned pile of synthetic green paint in a garage.

If you feel "off colour", it means you are feeling ill.  

A YouTuber, Rex Features, came up with an even better headline: Feline a little green?

Feline is a word used for members of the cat family, and feeling green, can mean you feel sick.