Not many people realize that when people talk about "pulling the plug," they're really talking about spark plugs.
Example
Loved One: I think I'm going to pull the plug.
NP: That'll mean less horsepower in your car if you do so.
Loved One: I know, but I think it's time to let go.
NP: I completely understand. (Short pause.) Are you sure you don't want to talk about anything else other than cars?