A Grilled Charlie is a sandwich masterpiece that Charlie has created. Charlie has tried to teach Frank the art of making a Grilled Charlie. Apparently the sandwich consists of two slices of bread, cheese and peanut butter on the outside and chocolate syrup and butter on the inside. (The Gang Goes Jihad)
Frank later asks Charlie to put rum ham on it as well, which results in him farting so tremendously that Charlie has him sit with his ass hanging out the window, which eventually leads to him falling out. (Frank Falls Out the Window)