Dear Mary: how do I hide my pregnancy from my boozy friends?

Q. We love having friends to stay at our house in Cornwall. One particular guest has the habit of arriving with the contents of her fridge, which she crams into mine. This can range from a two litre bottle of milk with enough left in it for a cup of tea, to a pot of half-eaten hummus which has had its lid replaced by a piece of crumpled foil, to a half-eaten pack of blueberries which are going mouldy.