Jenna is a sentient lump of coal who appears twice during Freshly Baked: The Robot Chicken Santa Claus Pot Cookie Freakout Special: Special Edition.
First she appears during Krampus' song performing with "KRAMPUS + THE COAL LUMPS". When Krampus sings "never returns oral sex" and the Lumps sing in unison "that's ruuuude" Krampus retorts "yeah! That's the WORST, Jenna" and the lump wearing a red bow on her head holds her arms out and shrugs.
She then recurs at the end of the episode, turning over and going to sleep after Krampus finishes servicing her under the covers, causing him to complain "you have GOT to me shitting me right now, Jenna!"