It first aired on February 16, 2018.
The Futon Critic
Unikitty leads a blindfolded Puppycorn out of the castle. She tells him he can see the surprise now, which he thinks is a rock, but is really a massive birthday party. He gives a happy birthday to her, but he is even happier to find out it's his. Unikitty presents him his presents. She says it'll get even better with his cake. The birthday candle will let him have any wish.
Unikitty has invited everyone in the kingdom, including Master Frown and Brock. Puppycorn is angry about this as Master Frown ruins his party. He then also explains birthdays in a negative light, causing Puppycorn to say birthdays are the worst. Unikitty growls and tells him how mean that is and tells him to leave. Master Frown says he'll leave, but takes Puppycorn's candle in the process and they speed away.
Dr. Fox had upgraded their vehicles in case of any emergency, and they head to Frown Town. As Master Frown and Brock argue about when he makes the wish, (because of Frown never cleaning the dishes) Unikitty and Puppycorn notice all the gloomy aspects of the town. They are unable to locate Master Frown, so they check a map, but there is a line and an old man goes into a story about his life and how it went downhill.
Puppycorn is doubtful they'll get his wish back, only to discover his car. Unikitty calls for Master Frown and politely asks for their wish back, obviously not working. Master Frown jumps into his car and it becomes a fighting robot. Unikitty and Puppycorn fire shots from their vehicle, only for Master Frown to block them. Puppycorn realizes there's almost no time left for the candle and Master Frown destroys his vehicle.
Unikitty activates the emergency button and gets her own fighting robot. Master Frown yells he has a wish to say, which gives her an idea. Unikitty feigns defeat as Master Frown wishes no one can every make wish again, but because of saying it out loud, an explosion occurs and the candle is brought back to full size. Puppycorn blows on the new candle, granting him a ball. (With his name on it) Unikitty invites the whole kingdom to Frown Town. During the party, Unikitty tells him that his cloak's on fire. He wishes that he wasn't on fire, but Unikitty tells him it won't come true because he said it out loud.
For a full transcript of "Birthday Blowout", click here.
This episode was played at the San Diego Comic-Con 2017 panel for Unikitty! on July 20, 2017. This episode aired on television on February 16, 2018 on Cartoon Network in the United States, and received a total of 652,000 viewers. It also aired on March 12, 2018 in the United Kingdom.