Nobody move! It's a McBooger sister standoff!!!
Max and Phoebe track down their aunt for their mom's birthday only to find out that the sisters have been fighting for years.
Max calls for an emergency meeting for his band to discuss the failed gig last night. No one attended the band gig because Phoebe hosted an ice-skating party inviting the whole school. Oyster and Gideon wonder how Phoebe got the ice during summer. Max almost accidentally reveals that Phoebe did it using her freeze-breath but he says it's because Phoebe has an icy heart. He tells them that Phoebe is not a nice person. The meeting is adjourned when Phoebe arrives with snacks.
Tension rises between Phoebe and Max as they discuss what to get their mom for her birthday. Max is still mad about Phoebe throwing an ice-skating party at the same night as the band's gig. They start fighting using their powers until Barb gets into the living room and asks them to cool it. She tells them that they should be grateful to have each other as it would be horrible living without seeing each other. Max and Phoebe ask how come they've never met Aunt Mandy if Barb were so close with her sister. Barb claims that Mandy is too busy saving the world. She begs them to at least get along for her birthday - it would be the best gift. As Barb walks out, Max and Phoebe promise not to get along but instead give their mom a different gift: track down their Aunt Mandy and bring her over for Barb's birthday.
The Thunder Twins track down Aunt Mandy only to find that she is just in Metroburg. They find Aunt Mandy in a globe shop. She figures out that they are in fact Phoebe and Max Thunderman. They think that she is undercover using her invisibility power but she reveals that she owns the place. She happily accepts the invitation to Barb's birthday, promising a huge surprise.
Hank brings a chocolate munch-cake for Barb's birthday and instructs Billy and Nora to look after it. He bought it from a celebrity-owned bakery shop. Nora and Billy are happy that Hank has given them a responsibility. But before completing the sentence, Chloe takes a bite out of the birthday cake. Now Billy and Nora must cover up and get another cake before anyone discovers it. They ask Chloe to teleport them to the celebrity bakery, owned by the "Deena Dessert Diva." Deena makes hilarious Twine videos where she turns people into dessert dummies, They watch a video of Deena attacking a customer with desserts.Deena tells them the cake is worth $100 but since they don't have the money, she asks them to be part of her Dessert Dummies Twine videos. Nora refuses and stands up against her. They teleport back home to look for cash.
Time for birthday dinner. Nora and Billy are nervous because they don't have cake yet. Max and Phoebe return from Metroburg with a surprise gift for Barb. Aunt Mandy turns visible! Surprise! She then tells Barb that this party is going to be her worst nightmare. Surprise number two! Barb and Mandy have a huge standoff. Hank tells the kids to stay off, revealing that their mom's maiden name is McBooger. Max and Phoebe laugh at the "McBooger" name. Max tells Phoebe that she can add destroying mom's birthday to the list of things she's destroyed this week. Phoebe realizes that Max is still mad about the gig and asks him to focus on figuring out why the McBooger Sisters hate each other. Mandy explains to them that she and Barb had a fallout and haven't spoken in a long long time. She turns invisible to sneak-attack them. Barb uses her Electress powers to attack the invisible Mandy with her energy beams. The McBooger sisters destroy a lot of stuff fighting each other. The rest of the family hides behind couches.
As the McBooger fight intensifies, Nora tries convincing Hank to cancel the birthday dinner so that she can throw out the birthday cake. But Hank really wants the cake.Billy, Nora, and Chloe return to the bakery.
Phoebe asks Mandy why she is so mad at Barb. Mandy turns visible again and explains what happened. 23 years ago, Barb and Mandy were part of a struggling dance crew called the "Electric McBooger Babes." Mandy booked a big gig but Barb bailed on her so that she can attend some random girl's cape ceremony. Barb thinks it's ridiculous for Mandy to be still mad at her for skipping the gig to attend her best friend's cape ceremony. Max is offended by what Barb did. Mandy turns invisible again and starts attacking the Thundermans. The family runs out of their own living room to hide in Max's Lair. Max locks the room with Thundertanium so Mandy can't get through. They're stuck there, wondering how long they will have to live there.
While still stuck in the basement, Phoebe and Barb agree that Mandy is crazy for being still mad at her for bailing on the Electric McBooger Babes. But Max sees it differently. He stands up for Aunt Mandy saying that it is more than just the little performance - her sister didn't show up for something that was important to her and it hurt. Max gets emotional while explaining this. Barb wonders why Mandy never told her she was hurt but Max explains that maybe Aunt Mandy isn't the "touchy-feely" type. Maybe it's just easier for her to fight it. Max gets more and more emotional and in fact he switches sides and goes upstairs to help Mandy win the McBooger sisters' beef.
This helps Phoebe realize that Max wasn't mad about Phoebe throwing a party during his gig. He was mad because his sister refused to attend the gig. Max loves Phoebe and it would have meant a lot if she attended. Phoebe feels guilty for hurting her brother and thinks of a way to make it up to him.
Meanwhile, at the bakery, Nora gives in and accepts to take the deal and become one of Deena's dessert dummies. However, the celebrity says the deal has expired and now she wants to smash dessert all over Chloe. Both Chloe and Nora are not happy about it. Deena tells Chloe to order a cream puff so that she can hit Chloe's face with cream using a giant slingshot. Chloe is worried and scared because Deena is too mean. They watch as Deena pulls the slingshot, then Nora stops her. Nora says she wants to do it herself. Whaaat? Chloe put them into that mess in the first place, so she deserves it. Deena is so pleased to hear this since there's nothing meaner than a sister smashing cream on a little sister. Nora takes on the slingshot, aims at Chloe. But just before she shoots, she aims it at Deena, covering her face with cream. Deena is embarrassed. Nora, Billy and Chloe take the opportunity to steal the cake and teleport back home.
Hours later after teaming up with Aunt Mandy, Max fills three huge popcorn balls. He uses his heat-breath to heat them up and just before popping, he throws them down his lair to hurt Phoebe, Barb and Hank. He and Mandy bond over how they're better than everyone else in their family. As the popcorn explodes, he hears someone screaming like a girl. Little does he know that they've already left the lair through a different door. Only Dr. Colosso got caught in the exploding popcorn. Phoebe and Barb had already left the lair to prepare a surprise for Max and Mandy.
Aunt Mandy and Max run outside after Phoebe and Barb only to find Max's Band outside, ready to perform. Phoebe apologizes to Max for missing his gig. Max tries to hide his emotions. Barb apologizes to Mandy too and they both agree to do one Electric McBooger Babes dance. Barb gets too dizzy dancing and accidentally knocks off the new cake that Nora and Billy worked so hard to get. Chloe and Hank starting eating the cake from the ground.
- Kira Kosarin as Phoebe Thunderman
- Jack Griffo as Max Thunderman
- Addison Riecke as Nora Thunderman
- Diego Velazquez as Billy Thunderman
- Chris Tallman as Hank Thunderman
- Rosa Blasi as Barb Thunderman
- Dana Snyder as Dr. Colosso (voice)
- Maya Le Clark as Chloe Thunderman
- Paula Christensen as Mandy McBooger
- Ashlee Füss as Deena
- It is hinted that Barb wants Max and Phoebe to get along because she doesn't want them to end up like she and Mandy did.
- Barb's "McBooger" maiden name is mentioned again in Better Off Wed during the Barb - Hank wedding flashback, which also explains why it's never used and why the kids didn't even know it.
- Aunt Mandy is the second relative introduced. The first one was Blobbin in Weekend Guest.
- Max almost accidentally mentions superpowers to Oyster for the second time in this episode. The first time was in Doppel-Gamers when both Max and Phoebe almost reveal they're supes when referring on how difficult it was to defeat the video game villain.
- Hank's love for food, cakes, snacks has been shown in multiple episodes throughout the show. His Thunder Van password is "hamburger".
- This is Barb's birthday episode. Hank's birthday episode was in Mall Time Crooks and the Thunder Twins birthday was in Have an Ice Birthday.
- This was the nineteenth episode filmed in season 3.
- It's revealed that Barb's maiden name is McBoogers.
- Mandy makes her debut.
- It is also revealed that Mandy is Barb's sister; and The Thundermans' aunt.
- The title of the episode is a reference to the song "Ain't Misbehavin'".
- Phoebe and Max both try to freeze echoter but its said if there freeze breath touches it freezes a whole city which they do in this episode 2 times