You speak Chinese to your foreign friends. You own a karaoke machine. None of your shoes have laces. Chinese stop you on the street to ask for directions. You leave the plastic on new furniture.
Forks feel strange.
You can spot the differences between the China News and the China Post. The shortest distance between two points involves going through an alley. You wear blue rubber flip-flops at work. People don't see you for months, and when they do, they don't ask you where you've been. Your deodorant stick has cobwebs on it.