The actual name of this character is Bella Twin #2, but the wiki does not allow for the inclusion of pound signs in article names.
Bella Twin 2 is portrayed by WWE star Brie Bella and appears in S8E9 "A Nightmare on State Street" alongside Bella Twin 1, who is portrayed by Brie's twin sister Nikki.
Gus is having one of his nightmares and has just gotten lost in a school boiler room when he sees several creepy children as well as the Bella twins. They are swinging a jump rope together while singing a disturbing nursery rhyme:
Weepy, weepy, you so sleepy
and the little kids are creepy
Watch us jump, you know it thrill you
Just for fun, we're gonna kill you
They then turn and reveal that the other half of their respective faces is severely burned. As they move towards Gus, they start laughing uproariously and reveal vampire-like fangs. Gus gets caught in an enormous spider web while backing up, and when the twins say "Look alive, playa" he starts getting pelted with dodgeballs from the little children. This causes Gus significant distress until he is finally lucky enough to wake up.