It was as though Barry appeared out of thin air, when he stepped in line behind the man at Jendry's. His speed was quick enough to where people couldn't see him until he slowed. With the possible exception of Pietro Maximoff. And because of his speed, he tended to eat quite a bit. So the man in front of him's order didn't seem too extravagant or too big. Not to Barry, at least.
He tended to out-eat most people he knew.
"A supreme pizza sounds pretty good right about now," Barry said, idly. He didn't usually make conversation with random strangers, but he was bored. He tended to do things he wouldn't usually do when he was bored.
When it was his turn to order, he ordered a supreme and a pepperoni pizza. He'd likely eat most of both.