"Mr. Butt" (stylized as "Mr Butt") is the first episode of Season 2 of Teen Titans Go! and the fifty-third episode overall. It first aired on 12 June 2014 on Cartoon Network.
Blackfire pays a surprise visit to her sister, Starfire, saying she wants to spend some quality time with her. The other Titans think that Blackfire is playing another trick, but Starfire is sure that this time Blackfire is serious about reviving their sisterly love.
Starfire is watering the daisies in the Titans' garden while singing. An intergalactic robot suddenly crashes into the flower bed, causing Starfire to notice her sister fighting the other robots. Blackfire greets Starfire and asks her to help with the robots. As they destroy robots left and right, Blackfire claims that she came to visit her baby sister, but Starfire says that she never wanted to spend time with her or showed any respect for her. Blackfire makes excuses about her behavior until they destroy all the robots. Starfire is reassured by her lies and becomes excited at the thought of becoming close. She hugs her sister and faile to notice her smirking.
Meanwhile, the Titans are relaxing on the couch when the Tamaranean sisters enter through the elevator. Starfire introduces Blackfire to her teammates, but they just shun Blackfire with dirty looks. Blackfire asks Robin if he missed her, but he declares that she is evil and claims to only be attracted to niceness. He pulls Starfire into the kitchen for a word. Starfire talks about how happy she is to be with her sister when all the Titans join in and protest by saying how evil she is, enraging her. She warns them of how broken she would become if Blackfire betrayed her again and is about to state how her anger would destroy all organisms on the planet, when Blackfire invites her sister to take part in a makeover. Starfire happily agrees, and Blackfire makes Starfire look almost exactly like her. After the makeiver and in her room, Starfire is spotted by one of the intergalactic robots. Blackfire hides behind a curtain and points Starfire out to the robots. Their scanners identify her as Blackfire and they take her to an alien prison.
Later on, Robin is excercising in the living room. Blackfire enters the room and watches his butt. She comments on how Robin has a nice butt and he ultimately realizes that Starfire is missing and sends the other Titans to dig up the yard as he believes she was buried. Blackfire reassures them and says that she sent Starfire to prison to live out her sentence and begins to call Robin "Mr. Butt." The Titans berate her for using Starfire after she trusted her, and Blackfire says that she never learned how to be a good sister. Cyborg grabs her and tells her to prepare for "sister school."
The first lesson is to listen. Cyborg demonstrates with Beast Boy, and gives him proper advice with a problem he has. He asks Blackfire to follow his example, but Blackfire instead yells at him to be a man. Beast Boy is terrified and runs away crying. Meanwhile, Starfire is in her cell and she swears to exact her revenge. She rips her uniform sleeves off, tatoos her arm with her eye beams, and performs pull-ups on the cell bars while heavily grunting.
The Titans begin another lesson: hugging. Robin demonstrates to Blackfire how to hug by embracing Cyborg. The others come in and prepare to be embraced. Blackfire punches away Beast Boy and Cyborg while Raven simply turns away before reaching her. Robin criticizes her terrible effort and attempts to do it himself, but Blackfire grabs him and squeezes him, ignoring his pleads for it to stop. Meanwhile, Starfire begins to change her appearance by shaving her head.
Back at the tower, Blackfire is sitting on the couch, channel-surfing, when the Titans begin the third lesson: roleplay. All the Titans enter the room dressed up and acting like Starfire. They attempt to come through to her about Starfire's relationship with her, but she interrupts them to look at Robin's butt. Robin is outraged, and asks how Starfire is able to love Blackfire through all of their dificulties. Blackfire realizes that Starfire had genuine affection for her. She experiencee a flashback of them as kids which shows how Starfire still loved Blackfire even after she took her favorite dolly. Blackfire decides that she wants to be a better sister and asks the Titans for help. At that same moment, Starfire is exercising while staring at a picture of her sister. She drops the weights as the word "revenge" is tatooed on her fist. She declares it's time for "sister fun time" and punches the picture. The wall gives out and Starfire flies out the prison on her way back to Earth.
Blackfire begins acting as a better sister. She gives Raven a makeover, makes Beast Boy feel better about his issues, and is given permission by Robin to call him "Mr. Butt." The Titans are pleased by how she has improved, and believe that Starfire will be happy to see her. At that moment, Starfire angrily bursts into the room. The Titans greet her, but she responds by punching Robin in the face. Beast Boy asks Robin, now called "Mr. Butt," if he is okay as Starfire confronts her sister. Blackfire tests out all the skills she learned to be a better sister, but Starfire is too enraged to notice. She claims it's too late to apologize and slams into Blackfire. They crash through buildings and tear the road until they crash into a clothes boutique.
Blackfire tries to talk to her, but Starfire is too angered to listen. Blackfire stops her to give her back the dolly she took from her as a child. Starfire sees it, and realizes how Blackfire has changed. However, Starfire claims she has changed as well and disintegrates the dolly in her hands. She thrusts a ball of enegy to Blackfire, and the ensuing explosion is seen all the way from Titans Tower. The Titans stare in shock at the wreckage, but turn to see Blackfire standing in the elevator. Robin asks how it went with Starfire, but she collapses in exhausation. Behind her, Starfire smiles and says that they worked things out.
Second time Starfire had her hair in a different color ("Nose Mouth").
The kazoo music played over the "Sister Fun Time!" montage sounds similar to the kazoo song played over montages on Elmo's World, a Sesame Street segment.
Earlier in the episode, Starfire says that Blackfire never visited, but after entering the tower, the other Titans already know the terrible things Blackfire has done. Blackfire even asked Robin if he missed her.
After Starfire destroys the mannequin that Blackfire proffers, it appears again then disappears.
The Image Gallery for Mr. Butt may be viewed here.