My roommate and I went to our usual ful (fava beans stew) and taamiya (falafel) stand around the corner after the gym tonight. As I was standing waiting for my sandwiches to be made I turned my head and smiled at the guy next to me, just as a kind of friendly gesture. The guy turned to me and here is the exchange which took place:
Guy eating taamiya sandwich: Please, have some (referring to his sandwich)
Me: No, thank you. Is it I good though?
Guy eating taamiya sandwich: Yes, very good. Are you Muslim?
This type of exchange is very common in Cairo. People are very friendly, and if you express any interest in something they have, they will often offer it to you, whether it be the food they are eating or the shirt they are wearing. When people offer you food, and they are eating a bag of chips for example, you can take a chip. My roommate, however, once took a sandwich from his taxi driver. You are not really supposed to do that. You also obviously don’t take the shirt.
Your religion is also public knowledge here. Unlike in the United States, the first or second thing people here might ask you when they meet you for the first time is if you are a Muslim.