What are some things you should never tease someone about?

I was just thinking about how my former BIL once made a teasing remark about my facial hair. (Don’t worry, I don’t have a beard.) I was thinking that is something you should never tease a woman about, Are there physical or other attributes that you should never tease someone about? Or does it depend on your relationship to them and how you think they’ll feel?

Just looking for some discussion – not something I am hurting about now.