Has been regarded as the best, worst, most over-told, most under-appreciated, most clever, and/or most lame joke in history. As with most well known jokes, there are many different versions, usually with small changes to the phrasing of their location and the first muffin's comment, but faithfully ending with "HOLY SHIT, A TALKING MUFFIN!".
So these two muffins are chillin' in a oven, right? The first muffin says to the second muffin: "Ahh! We're in an oven..." The second muffin says to the first muffin: "HOLY SHIT, A TALKING MUFFIN!"