Yes. Drive thrus are very repetitive. You'll developed a habit (good or bad) but it'll help you in the future. One of mine when I worked at KFC was exaggerating my greetings like, "Helllloooo, thanks for choosing KFC, how may I help you?" By dragging hello I was able to set myself up for the additional words and it flowed out quicker and quicker as I racked up repetitions. That lady sounds like a prick but to be fair she doesn't know you stutter so she thought you were some degenerate kid who needs education on how to properly greet someone. Next time that happens apologize and tell them you stutter at the window. You'd be surprised how understanding people can be when they're educated. If they continue to become hostile or rude I'd ask them to order in the store or find a different Tbell. Fuck ignorance keep doing you but stay eager to improve everyday