The practice of suspending a diet for a day to indulge in overeating. This phrase is inspired by J.R.R. Tolkien's The Hobbit in which it states that the eponymous creatures eat seven meals a day; first breakfast, second breakfast, elevensies, luncheon, tea, dinner, and supper.
I've been a good boy all week, but Saturday is my Hobbit Day so stand back and keep your fingers and toes well clear of my mouth when that drops.
I haven't eaten a carb in weeks, but I'm going to get my Hobbit on come Saturday.