Case for creepy: Yeah, it's supposed to be funny, but a song about a grandma who gets drunk on egg nog, then goes out alone without her medication — only to get killed in a hit and run (by Santa, no less) — is a little dark. And then the song goes on, describing her funeral, their first Christmas dinner without her, how her husband doesn't seem to care...it makes me feel more unsettled than amused.
Case for classic: Yeah, it IS supposed to be funny, and it is! Details like the hoof prints on grandma's head and the table settings made to match grandma's wig are specific and clever, and having a song so out of left field play between the endless by-the-numbers Christmas songs every year is more than welcome!