Food is classified as junk food primarily based on its nutritional value and preparation style, often characterized by high levels of sugar, salt, and unhealthy fats, while lacking essential nutrients. The discussion highlights a humorous take on the definition of junk food, suggesting that it may be linked to the quality of presentation, such as being served without elaborate garnishes. Participants express their favorite junk foods, including hamburgers, fries, shawarma, salty potato chips with clam dip, and desserts like chocolate ice cream and cheesecake. The conversation also touches on the nostalgic value of home-cooked meals, with references to hiring chefs and comparing them to family cooking, emphasizing that the quality of food can vary significantly based on preparation and personal preferences.