I work as a server and often get laughter. It’s undoubtedly rude, but never has it seemed intentionally malicious. Usually when I manage to tell them that I have a stutter, they quickly seem to understand. I think the most important thing is to recognize that these people likely aren’t laughing in a sense that they’re making fun of you, but it’s more of a comfort thing, if that makes sense. This is their coping mechanism to feel more at ease because they don’t understand what’s happening as you stutter.