I'll start with something that happened to me a few months ago at Subway...
I went up to the counter and requested my usual, a six-inch turkey sub. As I did so, the guy just stared at me, face full of horror.
"Ewww!" he said, quite loudly. "You like TURKEY?? That is SO. GROSS. How can you EAT that??"
The employee was fairly young, and I think he thought he was being funny or something...but WTF?! It wasn't like I ordered turkey slathered in peanut butter and dipped in Slurpie. If he personally doesn't like turkey, fine, whatever. But why on earth would he feel the need to comment on my order? (I'm sure that turkey is probably one of their most common orders, so he must be telling people that all day long...)
Can you imagine a world in which employees commented on customers' purchases? "Sir, that is the ugliest shirt I have ever seen! I certainly hope you aren't planning to pay actual money for it..." LOL