I run my own business and had a similar experience with a customer a few weeks back. I am having a relatively smooth day until on the way out she asked "I don't think I got your name." <sigh> so this is the moment the smooth day ends and I get monster stuck this time when she laughs and pulls the "don't tell me you forgot your name" line. I use that anger smooth-talking-energy to get out "No, I didn't forget my name, I have a stutter. and I would appreciate it if you didn't laugh at my disability". I don't know if she could see how angry I was (in my business, in my house, and literally laughing at me) or if it came off as more matter-of-fact, which was the intent. I dont remember what she said, I was too focused on harnessing that anger+embarrassment and riding the "just told someone off" high, I do remember she apologized and left. That is something I never could have said to a customer if I wasnt the boss, but it needs to be acceptable to say to people "you are being an ass and need to stop".