What Christmas song has the initial ymiflc by nd?

The Christmas song you are referring to with the initials "ymiflc by nd" is "You're a Mean One, Mr. Grinch" by Thurl Ravenscroft (often associated with Dr. Seuss's "How the Grinch Stole Christmas"). This classic song captures the essence of the Grinch's character and has become a holiday favorite.