Ayi: Is your roommate named Jack?
Me: No, his name is Sam.
Ayi: Oh. Someone called me and said they were a friend of Jack, they must've been talking about Bald Head
Me: Yeah, I don't know a Jack
'Bald Head' is a guy she works for who doesn't speak any Chinese and has a giant dog (my ayi is very talkative, so I know these things).
Most of us expats employ an ayi (Chinese word for aunt, but in this context basically means cleaning lady or nanny). They come in, wash our clothes, pick up all our stuff, but often - probably more often than not - we don't know each other's names.
Usually we just call our ayis 'ayi.' This isn't so weird because in Chinese you can call someone by their job and be polite, like "excuse me, skilled worker!" or "service person, we want the bill." But then it also does seem weird because here you have someone you're trusting with everything in your bedroom and bathroom and everywhere else and you have an anonymous relationship.
I know my ayi's name. She also works for a few of my friends and she loves to gossip about who broke up with who and who moved in with who and who has a lazy roommate who can't get a job... Still, it's difficult to know what to call her, so mostly I just use her full name, family and given. Often if you're speaking to someone older, but especially someone who is educated or in some sort of position of authority, you might call them "Teacher So-and-So." That wouldn't be appropriate, but she is 15 years older than me and has two kids, so calling her just by her first name might be too personal. Simply calling her 'Ms Wang' seems weird too.
But, like most Chinese people, her full name is only three syllables so it's not like it's a mouthful.