Reminds me of a tale I've told before on this forum.
Back in Yorkshire we did a Wedding at a posh venue for someone our female singer knew and was associated with music. Inbetween sets we were asked if the groom and a couple of his mates could do some songs after we had finished our second set. The guy who wanted to play my Bass had obviously enjoyed some of the refreshments and asked me if it was OK. I responded with 'Fine,as long as you give me the keys to your car' This took him aback and he did not understand why I was asking for his keys. I explained if any damage was caused to my Bass or rig, it would give me some collateral to negotiate restitution. In the end I relented and they were very accomplished players, I found out later 2 of them played for Embrace.....