Why I could never be a celebrity

I was walking through the cafeteria today, when a complete stranger came up to me and said "hey, Mr. Shirley, are you teaching 49B next quarter?" I really dislike when students do this. Mainly because I don't know the student from Adam. I love seeing students I know, but when a stranger comes up to me, it bothers me. This is why I could never be a celebrity. I'm a private person, and this kind of thing really throws me off.

I once had a student come up to me, as I was walking to my car, and said, "Because of you, my schedule is all messed up!". I had no idea what she was talking about (I didn't even realize she was a student, to be honest). It took her telling me how she was trying to get into my class, and rearranged her schedule, only to not get into my class, thus messing up her schedule. When someone says something like this to me, I think, "why the hell do you think I would care?" I don't even know who you are, and why would saying this as your first words to me, ever, help get in my good graces?

Back to the guy in the cafeteria...

Him: Hey, Mr. Shirley, are you teaching 49B next quarter?

Me (being curt): No.

Him: When are you going to teach 49B?

Me (being curt still): I dunno.

There was no thanking me for my time, or sorry to interrupt me from paying for my cookie, he just walked off. I thought that was kind of rude.