http://www.tripadvisor.com/Travel-g191-c3541/United-States:Customs.Habits.And.Etiquette.html http://www.tripadvisor.com/Travel-g191-c3541/United-States:C... Bu

http://www.tripadvisor.com/Travel-g191-c3541/United-States:Customs.Habits.And.Etiquette.html http://www.tripadvisor.com/Travel-g191-c3541/United-States:C... Bullet point #1. I would consider that fairly obvious. If you can't manage to stumble across #1 cultural tip then you obviously have not done much research. You shouldn't expect people to excuse your ignorance of their culture. That goes for any country - not just the US.