Coming to think of it, I actually once had a close encounter..Pretty sure it was a KL flight, MNL-AMS prolly. I was going to help myself to some mineral water when the FA stopped me. It was her "private water bottle" (placed on the shelf in the self service galley). And she could prove it, too. Yes, the water bottle did have her name on it, once it was turned around ( red marker pen , no less ).

Well, since I merely had touched the bottle, and not a drop was spilled, I was let go with a warning and a thorough lecture about the red ink marking system deployed for staff water bottles