Last time I was in the USA (Dallas), I ate Dominos pizza and my stomach was NOT used to that kind of processed fake food. My pulse was racing, I broke out in a cold sweat, and checked myself into a hospital. Hospital told me nothing was wrong, I felt like I was dying though. I went home after a couple of hours, then after it had passed later that night I realize it must have just been some kind of stomach reaction that caused it all. Ended up with a US$7000 hospital bill. True story.