The McDLT was promoted with the phrase “Keep the hot side hot and the cool side cool.”
The slogan explained the sandwich's unusual package. The cooked patty and bottom bun were placed in one compartment, while the lettuce, tomato, and top bun were placed in another. The customer joined the two parts immediately before eating, preserving a contrast between hot ingredients and chilled toppings.
This was a branding strategy as much as a packaging decision. McDonald's made the container easy to recognize in advertising and gave customers a simple action to remember. The slogan became closely associated with the product even though the sandwich itself was not a permanent menu item.
The McDLT is sometimes mixed up with McDonald's other specialty burgers from the 1980s and 1990s. Its defining feature was not merely the recipe; it was the split package and the accompanying hot-versus-cool message.