(The episode begins with Mordecai and Rigby cleaning the bathrooms; Mordecai is cleaning the girls' bathroom and Rigby is cleaning the guys' bathroom; Rigby is cleaning the mirror)
Rigby: Ugh, why can't I get this one spot?!
(Rigby breathes on the mirror and is about to wipe the mirror but letters are being written on the mirror backwards)
Rigby: Uh..... Mordecai?
(The letters spell "Ybgir" and Rigby underneath it)
(2 long black arms reach out to Rigby)
(Rigby screams as the arms pull him into the mirror; Rigby is in a world where everything is the opposite and Ybgir is in front of him showing his teeth)
Rigby: Hey Ybgir! Long time, no see. Do you mind bringing me back out there? I have work to do.
Ybgir: (Deep, snarled voice) No! After you made me return to this dimension, I've been waiting for this exact moment for you to come and let me take my revenge I've been waiting centuries for.
Rigby: Centuries? But I met you last year.
Ybgir: In this dimension, every day is a century. Hence why everything is opposite of itself in your dimenson. You must know how I feel being in this prison.
Rigby: Wait, what?!
(Ybgir grabs Rigby and chants something in an ancient language; Ybgir howls and Rigby screams as they switch bodies; Rigby shakes himself and looks in a mirror; it is revelead he's in Ybgir's body but is the same size as his own body; Ybgir is in Rigby's body and has a muscular body)
Rigby: What did you do?!
Ybgir: I simply switched our bodies. Now if you excuse me, I'm gonna go get some revenge.
(Ybgir shrinks into Rigby's size and jumps out of the mirror; Rigby tries to follow him but hits the mirror and can't get out)
Ybgir: So long, Ybgir.
(Ybgir laughs and walks out of the bathroom as Rigby looks on with a scared expression on his face; Mordecai walks up to Ybgir)
Mordecai: Rigby, what the heck was going on? I heard you screaming for me then you became silent.
Ygbir: Oh well.... I saw a spider and I killed it. I was gonna have you kill it but I killed it myself to save you the trouble.
Mordecai: Dude, did that spider bite you since your voice is deeper than usual.
Ybgir: Um yes. It did bite me but I should be fine soon.
Mordecai: Alright. Let's get back to the house and see what other dumb chores Benson has for us.
(Mordecai and Ybgir walk to the house; Scene goes to them in Benson's office)
Benson: Oh, there you are. I've been waiting for you to get back here. What took you so long?
Mordecai: Someone put gum on a bathroom stall and I had to scrap it off.
Ybgir: I was killing a spider.
Benson: Rigby are you sick? Since you don't sound like yourself.
Rigby: The spider bit me and my throat swelled a little. But I should be fine in a little bit.
Benson: Hm.....Anyway. Now I want you two to clean up all the trash you see that is not in the trash cans. Got that?
Mordecai: Got it.
Ybgir: We will do it.
Benson: Good. Now get to work.
(Mordecai walks out of the room but Ybgir stays)
Benson: Rigby, I said get back to work.
Ybgir: Benson, you seem tense. Here, let me help you relax by giving you a massage.
(Ybgir shows his fangs and claws and jumps on Benson; Benson pushes him off before he can be scratched)
Benson: Rigby! What's the matter with you?!
Ybgir: I was trying to give you a massage to get rid of the tension you have.
(Mordecai walks back in and Ybgir retracts his fangs and claws)
Mordecai: Is everything okay here? And Benson, why are you on the ground?
Benson: Rigby tried to kill me!
Ybgir: I was trying to be a good groundskeeper and help my boss by giving him a massage.
Mordecai: Okay then.....Come on dude.
(Mordecai leaves and Ybgir slowly follows; he looks at Benson and smiles; Benson looks at him startled; Scene goes to Rigby in the mirror dimension)
Rigby: Ok think. How could I be able to get out of here?
(Rigby looks at a mirror and has a excited face)
Rigby: By un-jinxing! Now I have to wait for someone to use this mirror and I can get out of here, find Ybgir and I can get my body back! And they say I'm dumb.
(A kid walks up to the mirror)
Kid: Ugh, I got mud in my hair. Hope my mom doesn't get mad.
(The kid makes his hair wet using the sink and walks away)
Rigby: I'm gonna be here awhile.
(Scene goes to Pops drawing a woodpecker on a tree when Mordecai and Ybgir walk up to him)
Pops: Hello Mordecai! Hello Rigby!
Mordecai: Hey Pops. Nice drawing.
Pops: Why, thank you. I have been practicing.
Ybgir: Can I see that?
Pops: Rigby, your voice. It's-
Ybgir: Spider bit me. I'm fine, really.
Pops: Oh, well sure. You can see it.
(Pops gives Ybgir the drawing and Ybgir rips the drawing up; Mordecai and Pops look at him with surprised faces)
Mordecai: Dude what the heck?!
Pops: Rigby, why would you do that?!
Ybgir: Whoops. I didn't mean to.
(Pops stomps away)
Mordecai: You just ruined Pops' drawing for no reason! You have to apologize to him or we'll be in trouble.
Ybgir: I prefer the trouble.
(Ybgir walks away smiling and Mordecai looks at him with anger; Scene goes to Mordecai, Benson, and Pops in Skips' garage)
Mordecai: Skips, we need your help.
Skips: What for?
Mordecai: Its Rigby.
Benson: Rigby's different and I don't think the spider that bit him made him like this.
Pops: He was very rude to me. He ripped up my drawing!
Benson: And he tried to attack me!
Skips: Wait. What do you mean hes 'different'?
Mordecai: His voice is way deeper than usual.
Benson: He also had sharp claws and sharp teeth.
Pops: And Rigby would like my drawing, not ruin it.
Skips: Hm....Get him here.
(Mordecai is seen dragging Ybgir to Skips' garage)
Ybgir: Where are you taking me?
Mordecai: To see Skips.
Ybgir: What for?
Mordecai: You'll see.
(Mordecai throws Ybgir into Skips' garage and Mordecai locks the door)