Do people actually do this?

At Tim Horton's last week I asked for a large coffee with two milks. Same as usual. I stood to the side, waiting for my order. A couple minutes later the woman behind the counter shot a panicked look in my direction and cautiously held out the coffee cup in front of me. "Ma'am, are you sure you want twenty milks in your coffee? Seems more like a latte." The cup was literally filled to the brim with cold milk.