Grinch Porn
While it might be stated, "the Grinch is always naked," implying that all Grinch-related media is Grinch porn, the truth is much bleaker. Grinch Porn is an actual thing, where a dude dressed as the Grinch bumps uglies with a chick in costume as a resident of Whoville.
"I feel the depravity of man weighing heavily upon my soul. I will embrace it and Google for Grinch Porn."