Register Clot
Derived from "blood clot", a register clot stops the flow of commerce by continuing to shop even though they have reached the cash register. They order cigarette cartons that are located in distant locked cabinets, paruse the lottery gaming options available to them, or wait for loved ones who are still retrieving that one can of refried beans that they forgot to pick up during their normal shopping rounds.
(husband & wife on cell phone)
Her: "Honey, are you on your way back from the market yet?"
Him: "I should be, but some damned Register Clot is still waiting for the clerk to return with the 2-for-1 brand of creamy peanut butter"...