Someone knowledgeable and/or of importance and high standing in an area or feild.
1. Stop addressing me as "Dr. Cox" in front of your patients. When they find out my actual name, they tend to page me with questions when they realize just exactly how inept you really are. Oh, and as an added safety measure, from now on, I'll only be responding to "Doc," "Doctor," "Ceasar," or "The Big Cheese;" and noooo, I'm _not_ joking.
2. My dad can get us on the moon within the hour. He's a big cheese at NASA...
A person of Chinese descent, who happens to be in a situation, although is not an essential part of it. Their presence isn't part of "the plan". The term is frequently used by university students, to describe their housemate constitution.
Possibly considered offensive.
Sarah: Who are you living with this year?
Sean: A guy called Rich who I lived with last year, Jesse, off our course and a chinese random...