Man if I had $5 for every time I’ve been asked “Can I Play Your Guitar?” I’d be rich! I’ve had people stumble up to me at gigs drunk out of their mind and ask if they can sit in with the band, and of course play my guitar to do it. I once had a guy grab my 2nd guitar off the stage while I was playing and play air guitar with it. Lucky for that guy he was a visiting Japanese dignitary at a marketing convention that didn’t speak any english. I think he knew enough from my reaction to quickly put my guitar back. I guess some words are universal. So when somebody asks me “Can I Play Your Guitar?” my policy is to simply say “No”. There are several reasons I’ve learned to just say no over the years.