I used to be a cashier. And I would have a couple of phrases ready in my head. So just in case I feel like Im about to stutter, I can say a different sentence instead. For example, We had to ask customers whether they want a bag or not. So, I can either say "Would you like a bag?" or, I can also say "Do you want a bag?". My point is, if you feel like youre about to stutter, rephrase you sentences. Instead of saying "Can I", you can say "May I".