"Birds" is Teen Titans Go! Season 1, Episode 21b, the overall 42nd episode of the series.
Robin removes two mockingbirds from the chimney with a gas he created in his lab, but the chemicals mutate the birds into muscular bullies who end up taking over the Tower.
The fire alarm suddenly starts to blast in Titans Tower. The Titans all begin to panic, until Raven figures out that the only problem is that the chimney is clogged. The Titans make Robin clean the chimney, even though he is the leader, it is his job. When he arrives at the top, he is disgusted to find two mocking birds inside. Robin orders them to leave, but they literally mock him. Robin decides to start sweeping them out, but they attack him and beat him up.
In the lab, Robin creates a special mixture of birdy-cide. Robin then goes to the roof, and poisons the chimney, causing the birds to flee. The birds hide behind some bushes, ashamed at their defeat. Suddenly, they mutate into two human-sized mocking birds. One of them turns blue, while the other turns orange. They begin to play music, which attracts the attention of the other Titans.
Robin stops sweeping the chimney when he hears the other Titans laughing and partying with the birds. The titans think the birds are super cool. Robin isn't able to recognize them at first, and introduces himself. They make fun of him for being a "robin without feathers". Robin asks them if they are mocking him, then realizes...they are the same birds he poisoned. The birds also realize that Robin mutated them. The two are ungrateful for their transformation, and attack Robin. Robin becomes jealous that Starfire falls in love with the blue bird. Robin warns the others that Mockingbirds are bad news, but they all ignore him. The birds enter Titans Tower, with the other Titans following behind.
Later that day, The birds are doing impressions of other birds for the Titans in the living room. When asked to do a robin, they make fun of their leader, not the bird. Only Robin is offended by this, and the birds secretly tell him that he is dead meat. This causes Robin to run away.
Later, when Robin tries to enter his room, he is disgusted to find the birds in his room with a giant nest. The birds tell him that since he took their nest, they're taking his. Robin finally becomes fed up, and decides to move out of Titans Tower. The other Titans don't hear him announcing his exit, but the birds do, who tell them not to worry. The birds decide to throw a bird party, and invite hundreds of random species of birds over to party.
A few days later, Starfire and Beast Boy become very annoyed with all of the random birds. When one of the birds attacks Cyborg for simply eating an egg sandwich, the Titans draw the line, and decide the birds need to go. The alarm goes off again, and the computer tells them that the chimney is clogged again. The birds force the Titans to go clean it, and watch TV while they work.
On the rooftop, the Titans decide that Robin was right, and regret ignoring him. The Titans become shocked when they realize what is clogging the chimney: Robin himself. Robin grew a beard, had old wrinkly clothing, and went insane. The Titans beg him to help them get rid of the birds, and he doesn't want to help. They then ask him to lead them, since he is their leader. Robin finally snaps out of his insanity and bursts out of the chimney, his beard shaven, and his suit repaired. Robin excitedly yells "TITANS, GO!"
The Titans burst into their living room and get into their battle poses. The birds become disgusted that Robin returned, and the Titans attack. Robin is easily beaten by a bird, but Beast Boy transforms into a tiger and tackles him. At first the Titans put up a good fight, but after major destruction damages the tower, the birds begin to win, and pin down the Titans against a wall. When asked how he got rid of them in the first place, Robin remembers he still has birdy-cide. Robin hands it to Cyborg, who fires it everywhere, causing the birds to mutate.
The birds are now mutated into having giant brains, and are superior beings. They tell the Titans they no longer want to battle, because they have evolved to superior intellect, and know the foolishness of violence. Robin realizes this is his opportunity, and begins to violently attack the birds. The birds flee Titans Tower, with Robin yelling at them. The Titans are glad to finally take back their Tower.
Meanwhile, in Robin's room, we see the nest the birds made. Suddenly, one of their eggs hatches, and a bright light fills the screen.
- The Mockingbirds talk in a Cockney accent. This is the first time we hear Scott Menville voice such an accent.
- It is revealed that Titans Tower has a chimney.
- This was the second leaked episode before its air date.
- When Beast Boy rolls on the ground, the running sound effect from Scooby Doo can be heard.
- Flex can be seen doing a reference to "The Knife Game Song."
- The famous "Wilhelm Scream" can be heard when the birds make their first mutation.
- The Blue Mockingbird's laser beam powers and square tinted shades ironically match the likes of Cyclops' from The X-men, a series owned by DC's infamous competitor, Marvel. While Cyclops is a hero in X-men, the Blue Mockingbird is a villain.
- Robin's drawings in the chimney are similar to the drawings by Rattmann from the Portal video games.
- When the mutant bird egg hatches at the end of the episode the crack and the bright green glow seen inside it may possibly be a reference to the theatrical poster for 1979 science-fiction horror film, Alien.
- Orange Mockingbird's purple Mohawk and shades are the same as those worn by the villain Bebop from the 1987 television show Teenage Mutant Ninja Turtles.
- The comedic face shown on the "Titan T.V. / Tracking Device" is the same face that was on the sweltering sun at the very beginning of "Hey Pizza!".
- The music heard when Robin first finds the mockingbirds is from "Nose Mouth".
- Robin tries to avoid doing chores again. ("Laundry Day")
- When Robin leaves the Titans, music from Grab That Grub and "No Power" is heard.
- When Beast Boy wakes up, music from "Tower Power" is heard.
- Robin once again writes on the wall after turning insane. ("Nose Mouth")
- Characters that appear during the "Bird Party":
- Cyborg repeatedly getting splashed with water and shorting out.
- "Are you MOCKING me?" - This line is used in more than one occasion of the episode.