Dr Williams?

Just happened: A guy walked in my office with a small box and says:
Guy: Can I leave this here for Dr Williams?
Me: I don't know Dr Williams.
Guy: For Doc-tor-Will-iams
Me: I don't know Dr Williams
Guy: He's a professor.
Me: I don't know him.
Guy: Dr Williams.
Me: No, I don't know him.
Guy: Are you sure?
Me: Never heard of him.
Guy: I thought this was his office?
Me: No, but it is my office.
Guy looks at the name on the door.
Guy: Do you know where Dr Williams office is?
Me: I don't know Dr Williams.
Guy: Where should I leave this package?
Me: In his office?
Guy: Do you know where that is?
Me: I've never heard of him.
Guy: Maybe I am on the wrong floor, isn't this 418?
Me looking at the number on door: No, it's 223
Guy walks out.
This building only has 3 floors.. *sigh*