Mouth Hole

"Mouth Hole" is the 25th episode of the second season of Teen Titans Go!, and the 77th overall episode of the series.

Summary
Robin goes on a quest to gain a new power: whistling.

Plot
The episode starts off with the Titans infiltrating the H.I.V.E. Tower to download their evil plans. Robin tells the Titans that he will use the communicator in case the H.I.V.E Five return. However, Beast Boy explains that's not an option, as the communicator was destroyed by Raven while he was pranking her. Cyborg then suggests to do it old-school, by whistling. Robin is hesitant, but the other Titans bolt into the H.I.V.E. Tower before he could say anything. Right after that, the H.I.V.E Five returns.

As the Titans are downloading the evil plans, they hear Robin unsuccessfully trying to whistle, and try to do "whistling sounds". They think it is not Robin, and compare it to many things, such as a dying bird, and someone who stepped on a jelly doughnut. The H.I.V.E arrive in that moment, choking Robin and they throw the Titans out of their Tower.

Back in the Titans Tower, all the Titans are injured, and Cyborg remembered him of telling him to whistle. Robin claims that he did whistle, but the conditions were not favorable for him. Raven then suspiciously asked him if he knows how to whistle, which he agrees. He then tries to whistle in front of the Titans, but fails, and spits in all of the Titans. Starfire told him to stop, and Cyborg said that he needed to learn to whistle in order to do many things (like call a cab or call a dog). And while Robin would never devote his time into doing such a stupid thing as whistling, Starfire then offered to teach him, as he immediately agreed.

On the Tower's roof, Starfire believes that it is the perfect climate to show Robin how to whistle, with no distractions, and plenty of air. Then Starfire starting singing beautifully, as Robin started to admire her. Starfire then says that it is his turn to whistle, and told him how to do it. He tried to whistle in a fake way, instead by trying to kiss her. He asked if he was doing it right, but Starfire showed her how to do it by forcefully pressing his lips. She cheered on as his lips became purple. When she let the lips go, she said that she did very well for her first try, and Robin thanked her.

Later on in the kitchen, Beast Boy and Cyborg start hearing a sound every time they do something, and the sound start driving them mad and nervous. When the girls enter and when Raven passes by Beast Boy, a wolf whistle is heard, and Raven thought it came from Beast Boy, as she slapped him literally, even though it wasn't him. When Starfire asked where it was coming from, Robin came out of the bushes. Starfire was overjoyed to see him whistle, even though he was only using a whistling toy. Beast Boy said that that was not whistling, but Robin claims that it clearly was, for he has, as always, exchanged a skill with a gadget. Cyborg then explained that whistling isn't like having superpowers, but a skill that everyone can master, like learning a language. They decide to do "Total Immersion Therapy".

Neither Robin, or the Titans could talk. They could only whistle. Robin asked how they would communicate, but he sees the Titans clearly communicating by whistling. Robin was about to ask them how they do it, but quieted him, and agreed to make a Whistle song purely out of whistling to teach or possibly teasing Robin. However, it fails. Robin gets outraged, and reminds them that the H.I.V.E is up to something. Raven asks him who is going to lead them, and Robin says himself. However, Beast Boy tells him he can't even whistle. Robin gets self-conscious because of that comment, and begs them to help him. Raven suggested a way, as she spawned her Ancient Legends book. She tried talking while whistling, but Robin couldn't understand her. She then said that he needs to find the master of whistles located in a castle fortress.

When he gets to the castle, the door closes by itself, which worries Robin. As the tension rose, a statue greeted him into the castle, which startled Robin. However, it was a tea pot. She asked him why he was there, and Robin said that he seeks the master of whistles. She then offers some tea, but Robin said he needed to find the master now, and not a Teapot. The Teapot then asks Robin if a teapot was all he needed, and Robin said yes, which angered the tea pod, and whistled so hard that she blew Robin off to the door. He then realized that she was the master. Robin wished he could whistle like that, and the Master said that he could, but he first needed to drink some tea. Robin thought it was to warm up, but when he drank it, he started choking. When he asked what was hat, the Master said it was hot sauce. As he was asking what it was, he started whistling perfectly. The Master says that once he knows how to do it, his training can begin.

One training montage later...

Robin's communicator showed up the H.I.V.E's back as they captured the Titans and he had to leave in order to rescue them. However, the Teapot claimed that he was not ready but when he stopped her whistle punch, she was convinced that he was ready as she lets him go. In the H.I.V.E Tower, Gizmo's Death Ray was complete, and almost ready to annihilate the Titans, when Robin showed up. When the H.I.V.E came to attack him, he defeated them all with whistling. And when Gizmo attacked him with his Death Ray, Robin defeated him reflecting his ray with his main powerful whistle ray enough to make a hole out of the Tower, and saved the Titans. Starfire was amazed by the whistle, and the episode ends with a cliffhanger, as Starfire and Robin were about to kiss while the other Titans were amazed by this moment.

Characters

 * Robin
 * Cyborg
 * Starfire
 * Beast Boy
 * Raven
 * See-More
 * Jinx
 * Mammoth
 * Gizmo
 * Billy Numerous
 * The Teapot Master (debut)

Songs

 * Whistle Song

Trivia

 * Robin is shown to whistle in the previous episode, suggesting that this episode takes place before then.
 * This episode was supposed to air on Thursday, November 20, 2014, but was replaced by "Road Trip" for unknown reasons.
 * This is the first episode of Teen Titans Go! that premiered in 2015, and also the second episode since the show went on hiatus after the previous episode, "The Best Robin", which aired on Thursday, December 4, 2014, once again, due to the holidays.
 * Due to being the first episode aired in 2015, channel guides misidentify this episode as being the premiere for a non-existent (as of now) third season. All episodes that aired after this one are also considered part of this "Season 3" by the channel guides.
 * This episode aired one year after "Nose Mouth", and oddly enough, both episodes have similar names.
 * It is unknown if Robin and Starfire actually kissed, for the episode ended in a cliffhanger. Even so, it is implied that they did.

Continuity

 * The H.I.V.E. Tower reappears for a third time in this episode, completely fine from its destruction in "In and Out". It's also the first time the tower was seen in Season 2.
 * It is revealed Starfire actually does has romantic feelings for Robin, indicating she was likely lying in "Sandwich Thief" despite the detector though she may have tricked the detector. Or perhaps she didn't fall for him yet at that time.
 * While it is stongly suggested that Starfire and Robin kiss at the end of the episode, in 'Tamaranian Vacation' Cyborg says: "And she never kissed you on your one mouth. Bummer", indicating that perhaps they never did kiss after the episode ended.
 * The music that was playing during Robin's whistle training was the same music from 'Staff Meeting' when Robin was battling the Magical Tree Custodians with the Universe Staff.

Errors

 * In "The Best Robin", Robin was able to whistle without trouble when calling forth Team Robin, as well as whistling in other episodes. However, in this episode, he is unable to whistle until he meets with the Whistle Master.

Running Gags

 * Robin's spitting out of his mouth attempting to whistle.