A friend will help you move, a really good friend will help you move a body!
Bob & I have been business partners in a telephone answering service/call center for 36 years. Only twice have we nearly murdered each other, but we've rescued each other a couple of dozen times each. He's wired up every new computer I've ever bought, and repaired half of the ones that have broken. I owe him.
I'd turn down most of my blood relatives without any hesitation - and I'd be honest while using the classic Dr Phil line... so you've lost your job, and your dad won't take you in, and your sister has a restraining order.... and so... how is that MY problem?
In less drastic cases I'd go with "I love you but you're a klutz. You're not wealthy... and if you return something it's damaged or broken, so - NO." (And in reserve - you're poor, clumsy, and careless - and how is any of that my problem?)
I still think it's a bad idea to loan vehicles, RV's, boats, etc. That second hand lawsuit thing doesn't happen very often but when it does it's life altering in a very bad way.
OTOH, knowing when to make an exception to a general rule is what keeps us human. I am getting some real entertainment along the way. Bob was putting his groceries in the fridge and went "damn, there's no room for a gallon of milk"... I reached over and pulled out the plastic insert in the the middle tray and smiled gently. He put the milk in the perfectly sized spot.
Bob last RV'ed in the 1970's and when he needed heat he called to ask "are there any matches here and where do I light the furnace?" I could here his relief I told him to just turn on the thermostat (he was loathe to think that I'd come over and stand out in the cold rain at night to light the furnace and water heater - but knew he shouldn't do it himself.)
The water heater took a bit of doing, because neither of us knew there was an on/off control for it on the trailer's front control center/entertainment system. But once we remembered - oh that's where the 12 volt
kill switch is located, looking at the others was logical. OOH, hot water in less than one minute is something I'm looking forward to myself. Wonder how long I'll be able to resist upgrading the Airstream?
Frank put in switches that turn lights on in the pantry and closets when the doors are opened. That's another perfect simple thing to have. It's like a backup camera... how did I ever do without one?