I'm sure all MNs know that cows' milk isn't good for cats. It upsets their digestion and they're better off with just water. However, supermarkets, pet stores sell a product that's non-diary called 'cats' milk' (I think it's non-lactose, possibly soya based?) I bought a bottle for my cat (she ignored it) and was telling my gentleman friend about the stuff. He looked amazed - and, quite seriously, said it must be ever so difficult to milk a cat!!! So did they have cat farms, he asked, with herds of cats that were regularly milked?
He was quite offended when I fell about laughing.