You, having an interest in Dean, always kept mental notes of his stories, memories, and experiences. One of those being how he never really had a traditional Thanksgiving. All of his memories of that holiday can only be described as "a bucket of extra crispy and John passed out on the couch,". So, this inspired you to fix up a real Thanksgiving meal for him. It included the whole works, turkey.. mashed potatoes..rolls..sweet potato...cranberry sauce..apple and pumpkin pie.. you name it.
You had invited Dean to join you before he had the chance to take off for another hunt. He accepted, and now he stood outside the door of your apartment, curious as to what you possibly made. He never really celebrated anything the traditional way, so this felt a bit odd to him.