RWQFSFASXC (aka RXQ) is a shadow version of Bonnie.
RXQ seems to be a black-colored version of Toy Bonnie with white glowing eyes and teeth.
RXQ is an easter egg that appears in your office.
In Ultimate Custom Night, he is a character that XOR can summon. When he is in your room, everything in front of you except for your desk turns black. When he goes away everything turns back to normal.
In FNaF 2, RXQ will crash your game when you see him.
RXQ's behavior IN UCN is like turning off the light systems when he is in your office, so everything is dark and the night guard will not be able to see anything in front of him until he goes away.
- He may be the "spirit" of the previous version of him (Bonnie) since the theory says that in the previous pizzeria Freddy, Bonnie, Chica and Foxy got destroyed by Purple Guy, this is what the theory says, so it's possible that RXQ is the shadow of Bonnie that now is named Withered Bonnie.
- In FNaF AR, Shadow Bonnie is comprised of Dark remnant.