I'm surprised that nobody has mentioned this yet, but you need to escalate this to a higher up. It wasn't very clear whether you were talking to your manager or coworker (the one that snapped at you), but I'm going to assume it was the coworker. Talk to the manager about the incident. Maybe come in ten minutes early on your next shift and have a chat with them. Tell them what happened. Try not to be emotional, and stick to the facts. You have a stutter. You stuttered when attempting to communicate. Your coworker reacted in an aggressive and unprofessional manner and you'd like the manager to know so hopefully they can do something about it. If they don't remedy this, they are opening themselves up to a lawsuit since speech dysfluency is considered a disability, and assuming you are in the US, you are protected by the ADA from events such as this. I wouldn't bring up the ADA except as a last resort, though, otherwise they might figure that *you're* the liability and fire you for "unrelated" reasons, and it'll very difficult to prove that they fired you because of your stutter. I personally fucking hate the way customers laugh at my stutter, but that's not something that's in my employers' control, so I just have to grit my teeth a bare it. But if it were a coworker giving me shit for it? Manager time.