Gnome in your Home is a parody of the Elf on the Shelf. It first appeared in the episode, "The Nightmare after Krustmas".
The Gnome in your Home is a toy that is actually alive. Marge placed the Gnome in Maggie's room to watch her and make sure she was good. However, whenever her parents weren't around, the Gnome would come to life and try to kill Maggie. Maggie eventually got sick of it and ran him and his entire family over with a lawnmower and took a picture and sent it to her parents as a Christmas card.