At the movie theater I worked
I used to work at this fancy little one screen movie theater. It was a slow night, he came in with his mom and brother to see some kids movie. Nobody was there and nobody was bothering him, because I understand that could've put him in a bad mood, but he seemed fine when he came in.
So I got them their tickets and he ordered a "large bottled water," I told him we only had one size and it was your average bottled water. I handed him one and he looked at it like I'd handed him a dead cockroach covered in shit.
Then in this whiny, bratty voice he said, "What is this? This is like....a sip. Seriously. I'm obviously going to need two of these and I'm sure it's going to cost like fifty dollars."