Discussion Forum—A Way with Words, a fun radio show and podcast about language

I have heard the phrase "step away from the ... " used in many, many situations, with many, many different objects named at the end. It often has the gentle lilt of adressing someone who needs careful handling. The implication is that the person is about to do some great harm to himself or others, often by means of the object in question.

To me, it summons the image of a police intervention:
"Step away from the vehicle."
"Step away from the hostages."
"Step away from the ledge." (NOTE: I suspect you have to be very careful to establish directionality before uttering this one.)

Now, I wouldn't be surprised to hear:
"Step away from the cheesecake."
"Step away from the paintbrush."
"Step away from the thighmaster."
"Step away from the keyboard." (computer or piano)

Is there an iconic use of this phrase that launched it?