Name: Serial houseguests. Age: As old as the oldest dwelling. Appearance: Regular and unrelenting. You know what they say: houseguests, like fish, start to stink after three days. I think that rather depends on the guest. I’m sorry, but the rule has no exceptions. Not even Elon Musk? Why would Musk be anyone’s houseguest? Doesn’t he live in a solid gold mansion on the moon or something? No, nothing like that. So where does he live? You know, around. You mean he has lots of houses all over the place? He doesn’t have any houses. Then where does he sleep? He’s a serial houseguest. “I don’t even own a home right now,” he said in a recent interview. “I’m just literally staying at friends’ places.” This is Musk the rich guy, right? The one who just tried to buy Twitter for $43bn? Yes, he’s the world’s richest man. And he’s couchsurfing? Maybe not quite. “If I travel to the Bay Area, which is where most of Tesla’s engineering is,” he said, “I basically rotate through friends’ spare bedrooms.” How irritating. Musk was responding to a question about people’s hatred of billionaires, and pointing out his relatively frugal approach to life. Last year, he announced he was getting rid of his possessions. It’s one thing to have admirably modest outgoings; it’s quite another to be a constant imposition. We don’t know that he’s an imposition – maybe his friends are really pleased to see him. I’m sure. “Oh look, it’s Elon at the door with another suitcase full of dirty laundry. How thrilling!” He wasn’t specific about the arrangements, so it’s hard to … “A hotel? Don’t even think about it! Stay as long as you like, shave in the downstairs loo, finish all the milk and then bore us about the future of artificial intelligence!” Maybe he’s handy with broken appliances, or relationship advice. “Guess what, Elon! After your last visit I found this scrunched up $1m bill in the dryer. Do you think it might be yours?” This is all speculation on your part – it has no basis in … “Also this pillowcase with the insignia of your private jet on it. Don’t worry, I’ve ironed it.” Still, I’ll bet he remembers to send a nice note afterwards. I’ll bet he doesn’t. No, you’re right. Do say: “The week of the 15th? I think we might be away.” Don’t say: “The wifi password is GETYOUROWNPLACEELON, all uppercase.”