I'm a consulting detective. The only one in the world. I invented the job.
It means whenever the police are out of their depth — which is always — they consult me.
John Watson: That was amazing.
Sherlock Holmes: You think so?
John Watson: Of course it was. It was extraordinary. It was quite... extraordinary.
Sherlock Holmes: That’s not what people normally say.
John Watson: What do people normally say?
Sherlock Holmes: "Piss off!"