Rob

“On Twitter not too long ago, I was discussing the term “dope slap,” which I had traced back (using what was available to me at the time) to Tom Magliozzi, one of the hosts of NPR’s show Car Talk. A dope slap is, as Ray Magliozzi, Tom’s brother, says, “kind of a quick slap to the back of the head when the recipient is unaware that it’s coming,” and when Tom Magliozzi first used it in a Car Talk blog post, it was clear that the dope slap got its name from the dopey target of the smack: “Well, the first thing I’d do is give that kid a dope slap for driving home after the oil light came on. When the oil light comes on, you should always stop the engine immediately.” “I scoured all my sources and found nothing earlier than that,” I said. “Which means that someone will antedate it immediately.”
― Kory Stamper, Word by Word: The Secret Life of Dictionaries