Decades ago late one night at the Hotel Bel Air, I had only my client's first name and his NY cell phone. But there was, and probably still isn't, good ATT reception in Bel Air. It took a lot of calls from gate security to the manager to get them to call the guest with, luckily, a unique first name. Eventually, they let me in and boy was he young and rich and fun. No one famous.
Another story I've told here too often was the OC client who wanted me to strip fully down then knock naked on his Beverly Hills Peninsula room door at 4am. I took the dare, but chickened out mostly: the area around his door wasn't quite as private as he sold it, I took off just my shirt, I looked naked through his peephole and he opened the door :-) Strange fun guy, he had a lot of bad notices on the old old (Raphael Alencar sponsored?) blacklist site, but I think that was just because he was unique and demanding and British. He would often threaten to not pay, but that seemed more like just a kink. I digress.