Not The Brightest Spark

(I work at a fairly popular oil change service center where we do much more than just oil changes. This conversation happens more often than it should.)

Me: “And your manufacturer recommends having your spark plugs replaced every 105,000 miles.”

Customer: “I don’t think my car has spark plugs.”

(I stare at the customer to see if she’s kidding:)

Me: “Do you put gas in your car?”

Customer: “Yes?”

Me: “Then it has spark plugs.”